Synthetic cationic helical polypeptides for the stimulation of antitumour innate immune pathways in antigen-presenting cells

Intracellular DNA sensors regulate innate immunity and can provide a bridge to adaptive immunogenicity. However, the activation of the sensors in antigen-presenting cells (APCs) by natural agonists such as double-stranded DNAs or cyclic nucleotides is impeded by poor intracellular delivery, serum stability, enzymatic degradation and rapid systemic clearance. Here we show that the hydrophobicity, electrostatic charge and secondary conformation of helical polypeptides can be optimized to stimulate innate immune pathways via endoplasmic reticulum stress in APCs. One of the three polypeptides that we engineered activated two major intracellular DNA-sensing pathways (cGAS-STING (for cyclic guanosine monophosphate-adenosine monophosphate synthase-stimulator of interferon genes) and Toll-like receptor 9) preferentially in APCs by promoting the release of mitochondrial DNA, which led to the efficient priming of effector T cells. In syngeneic mouse models of locally advanced and metastatic breast cancers, the polypeptides led to potent DNA-sensor-mediated antitumour responses when intravenously given as monotherapy or with immune checkpoint inhibitors. The activation of multiple innate immune pathways via engineered cationic polypeptides may offer therapeutic advantages in the generation of antitumour immune responses.

Institution-Wide Retreats Foster Organizational Learning and Action at a Comprehensive Cancer Center

Providing safe and informed healthcare for sexual and gender minority (SGM) individuals with cancer is stymied by the lack of sexual orientation and gender identity (SOGI) data reliably available in health records and by insufficient training for staff. Approaches that support institutional learning, especially around sensitive topics, are essential for hospitals seeking to improve practices impacting patient safety and research. We engineered annual institutional retreats to identify and unify stakeholders, promote awareness of gaps and needs, identify initiatives, minimize redundant projects, and coordinate efforts that promote improvements in SGM cancer care, education, and research. The 2022 and 2023 retreats employed a 4-h hybrid format allowing virtual and in-person engagement. Retreat organizers facilitated small-group discussions for brainstorming among participants. We performed descriptive statistics from retreat evaluations. The retreats engaged 104 attendees from distinct departments and roles. Participants expressed robust satisfaction, commending the retreat organization and content quality. Notably, the first retreat yielded leadership endorsement and funding for a Quality Improvement pilot to standardize SOGI data collection and clinical staff training. The second retreat provided a platform for updates on focused efforts across the institution and for receiving direction regarding national best practices for SGM care and research. We report the processes and outcomes of institution-wide retreats, which served as a platform for identifying gaps in organizational healthcare practices and research for SGM individuals with cancer. The strategies described herein may be readily scaled at other cancer hospitals seeking to learn and enact system-wide practice changes that support the needs of SGM patients and families.

Optimizing Outpatient Radiation Oncology Consult Workflow by Using Time-Driven Activity-Based Costing: Efficiency and Financial Impacts

PURPOSE

Clinical efficiency is a key component of value-based health care. Our objective here was to identify workflow inefficiencies by using time-driven activity-based costing (TDABC) and evaluate the implementation of a new clinical workflow in high-volume outpatient radiation oncology clinics.

METHODS

Our quality improvement study was conducted with the Departments of GI, Genitourinary (GU), and Thoracic Radiation Oncology at a large academic cancer center and four community network sites. TDABC was used to create process maps and optimize workflow for outpatient consults. Patient encounter metrics were captured with a real-time status function in the electronic medical record. Time metrics were compared using Mann-Whitney U tests.

RESULTS

Individual patient encounter data for 1,328 consults before the intervention and 1,234 afterward across all sections were included. The median overall cycle time was reduced by 21% in GI (19 minutes), 18% in GU (16 minutes), and 12% at the community sites (9 minutes). The median financial savings per consult were $52 in US dollars (USD) for the GI, $33 USD for GU, $30 USD for thoracic, and $42 USD for the community sites. Patient satisfaction surveys (from 127 of 228 patients) showed that 99% of patients reported that their providers spent adequate time with them and 91% reported being seen by a care provider in a timely manner.

CONCLUSION

TDABC can effectively identify opportunities to improve clinical efficiency. Implementing workflow changes on the basis of our findings led to substantial reductions in overall encounter cycle times across several departments, as well as high patient satisfaction and significant financial savings.

Implementation and Efficacy of a Large-Scale Radiation Oncology Case-Based Peer-Review Quality Program across a Multinational Cancer Network

PURPOSE

With expansion of academic cancer center networks across geographically-dispersed sites, ensuring high-quality delivery of care across all network affiliates is essential. We report on the characteristics and efficacy of a radiation oncology peer-review quality assurance (QA) system implemented across a large-scale multinational cancer network.

METHODS AND MATERIALS

Since 2014, weekly case-based peer-review QA meetings have been standard for network radiation oncologists with radiation oncology faculty at a major academic center. This radiotherapy (RT) QA program involves pre-treatment peer-review of cases by disease site, with disease-site subspecialized main campus faculty members. This virtual QA platform involves direct review of the proposed RT plan as well as supporting data, including relevant pathology and imaging studies for each patient. Network RT plans were scored as being concordant or nonconcordant based on national guidelines, institutional recommendations, and/or expert judgment when considering individual patient-specific factors for a given case. Data from January 1, 2014, through December 31, 2019, were aggregated for analysis.

RESULTS

Between 2014 and 2019, across 8 network centers, a total of 16,601 RT plans underwent peer-review. The network-based peer-review case volume increased over the study period, from 958 cases in 2014 to 4,487 in 2019. A combined global nonconcordance rate of 4.5% was noted, with the highest nonconcordance rates among head-and-neck cases (11.0%). For centers that joined the network during the study period, we observed a significant decrease in the nonconcordance rate over time (3.1% average annual decrease in nonconcordance, P = 0.01); among centers that joined the network prior to the study period, nonconcordance rates remained stable over time.

CONCLUSIONS

Through a standardized QA platform, network-based multinational peer-review of RT plans can be achieved. Improved concordance rates among newly added network affiliates over time are noted, suggesting a positive impact of network membership on the quality of delivered cancer care.

Patient-Reported Sexual Function, Bladder Function and Quality of Life for Patients with Low Rectal Cancers with or without a Permanent Ostomy

BACKGROUND

Despite the increasing utilization of sphincter and/or organ-preservation treatment strategies, many patients with low-lying rectal cancers require abdominoperineal resection (APR), leading to permanent ostomy. Here, we aimed to characterize overall, sexual-, and bladder-related patient-reported quality of life (QOL) for individuals with low rectal cancers. We additionally aimed to explore potential differences in patient-reported outcomes between patients with and without a permanent ostomy.

METHODS

We distributed a comprehensive survey consisting of various patient-reported outcome measures, including the FACT-G7 survey, ICIQ MLUTS/FLUTS, IIEF-5/FSFI, and a specific questionnaire for ostomy patients. Descriptive statistics and univariate comparisons were used to compared demographics, treatments, and QOL scores between patients with and without a permanent ostomy.

RESULTS

Of the 204 patients contacted, 124 (60.8%) returned completed surveys; 22 (18%) of these had a permanent ostomy at the time of survey completion. There were 25 patients with low rectal tumors (≤5 cm from the anal verge) who did not have an ostomy at the time of survey completion, of whom 13 (52%) were managed with a non-operative approach. FACTG7 scores were numerically lower (median 20.5 vs. 22, p = 0.12) for individuals with an ostomy. Sexual function measures IIEF and FSFI were also lower (worse) for individuals with ostomies, but the results were not significantly different. MLUTS and FLUTS scores were both higher in individuals with ostomies (median 11 vs. 5, p = 0.06 and median 17 vs. 5.5, p = 0.01, respectively), suggesting worse urinary function. Patient-reported ostomy-specific challenges included gastrointestinal concerns (e.g., gas, odor, diarrhea) that may affect social activities and personal relationships.

CONCLUSIONS

Despite a limited sample size, this study provides patient-centered, patient-derived data regarding long-term QOL in validated measures following treatment of low rectal cancers. Ostomies may have multidimensional negative impacts on QOL, and these findings warrant continued investigation in a prospective setting. These results may be used to inform shared decision making for individuals with low rectal cancers in both the settings of organ preservation and permanent ostomy.

Improving radiotherapy in immunosuppressive microenvironments by targeting complement receptor C5aR1

An immunosuppressive microenvironment causes poor tumor T cell infiltration and is associated with reduced patient overall survival in colorectal cancer. How to improve treatment responses in these tumors is still a challenge. Using an integrated screening approach to identify cancer-specific vulnerabilities, we identified complement receptor C5aR1 as a druggable target, which when inhibited improved radiotherapy, even in tumors displaying immunosuppressive features and poor CD8+ T cell infiltration. While C5aR1 is well-known for its role in the immune compartment, we found that C5aR1 is also robustly expressed on malignant epithelial cells, highlighting potential tumor cell-specific functions. C5aR1 targeting resulted in increased NF-κB-dependent apoptosis specifically in tumors and not normal tissues, indicating that, in malignant cells, C5aR1 primarily regulated cell fate. Collectively, these data revealed that increased complement gene expression is part of the stress response mounted by irradiated tumors and that targeting C5aR1 could improve radiotherapy, even in tumors displaying immunosuppressive features.

Endoscopic Ultrasound-Guided Fiducial Placement for Stereotactic Body Radiation Therapy in Patients with Pancreatic Cancer

Accurate delivery of stereotactic body radiotherapy (SBRT) to pancreatic tumors relies on successful EUS-guided placement of fiducial markers. The aim of this study is to report the technical feasibility and safety of EUS-guided fiducial placement and to evaluate the characteristics and technical benefit of SBRT in a cohort of patients with pancreatic cancer (PC). A retrospective chart review was performed for all (n = 82) PC patients referred for EUS-guided fiducial placement by a single endosonographer at a tertiary cancer center. Data regarding EUS-related technical details, SBRT characteristics, adverse events, and continuous visibility of fiducials were recorded and analyzed. Most patients included in the study had either locally advanced disease (32 patients, 39%) or borderline resectable disease (29 patients, 35%). Eighty-two PC patients underwent the placement of 230 fiducial markers under EUS guidance. The technical success rate of the fiducial placement was 98%. No immediate EUS-related adverse events were reported. The average time to the simulation CT after fiducial placement was 3.1 days. Of the 216 fiducial markers used for the SBRT delivery, 202 fiducial markers were visible on both the simulation CT and the cone beam CT scan. A median dose of 40cGY was given to all the patients in five fractions. Of these, 41% of the patients reported no SBRT-related toxicities during the follow-up. Fatigue and nausea were the most reported SBRT-related toxicities, which were seen in 35% of the patients post-SBRT. Our results demonstrate that EUS-guided fiducial placement is safe and effective in target volume delineation, facilitating SBRT delivery in PC patients. Further clinical trials are needed to determine the SBRT-related survival benefits in patients with pancreatic cancer.

Salvage Abdominoperineal Resection for Locally Recurrent or Persistent Anal Squamous Cell Carcinoma after Definitive Chemoradiation

PURPOSE/OBJECTIVE(S)

Initial treatment for patients with squamous cell carcinoma of the anal canal includes definitive chemoradiation. Salvage abdominoperineal resection (APR) is the treatment of choice for recurrent or persistent disease. Older studies suggest approximately 50% successful salvage of recurrent or persistent disease with APR. Risk factors for failure after salvage APR are incompletely characterized.

MATERIALS/METHODS

Using a single institutional database, patients were identified who underwent salvage APR after definitive intensity-modulated radiotherapy-based chemoradiation between 2003 and 2022. Clinical and pathologic variables analyzed included age at APR, sex, race, HIV status, initial cT stage, initial cN stage, radiation dose, recurrent vs persistent disease, recurrent pT stage, recurrent pN stage, the presence of LVSI, PNI or <2mm surgical margins, and the use of either intraoperative radiation or another treatment modality in addition to APR. The log rank test was used to determine differences in time from APR to events (local recurrence, distant metastasis and death) based on clinical and pathologic variables. The Cox Proportional Hazard Model was used to perform multivariable analysis for all factors with a univariate P-value <0.1.

RESULTS

Of 628 patients with anal squamous cell carcinoma, 50 (8.0%) were treated with abdominoperineal resection for locally recurrent (n = 29, 58%) or locally persistent (n = 21, 42%) disease. Median [interquartile range] follow up was 40.0 months [15.2-68.0 months] from APR. Median local recurrence-free survival was not reached; 1- and 2-year local recurrence-free survival was 81% (95% CI 72-92%) and 76% (64-89%). On multivariable analysis, pathologic T-stage of the recurrence (3.85 (1.07-13.9); P = .040), the presence of lymphovascular space invasion (9.1 (1.12-73.62); P = .038) and surgical margins <2mm (8.81 (2.11-36.73); P = .003) were all significantly associated with higher rates of local recurrence. Median distant metastasis-free survival was not reached; 1- and 2-year distant metastasis-free survival was 88% (81-98%) and 79% (67-92%). On multivariable analysis, only persistent (versus recurrent) local disease was significantly associated with higher rates of distant metastasis (1.23 (1.05-5.55) P = .043). Median overall survival was not reached; 1- and 2-year overall survival was 90% (81-98%) and 78% (65-90%). On multivariable analysis, only recurrent pT stage (T3/4 vs T1/2) was associated with higher rates of death (5.87 (1.02-33.65); P = .047).

CONCLUSION

APR is a successful salvage modality for anal squamous cell carcinoma with recurrent or persistent disease after chemoradiation results. Patients with pT3/4 disease, lymphovascular space invasion, surgical margins <2 mm may be associated with higher re-recurrence rates and may benefit from more frequent monitoring or treatment escalation.

Feasibility and Clinical Implementation of Electron FLASH Radiation Therapy in the Yorkshire Swine Model

PURPOSE/OBJECTIVE(S)

Preclinical studies have shown FLASH radiation therapy (RT) increases the therapeutic index through reduction in normal tissue toxicity but with retained tumor control compared to conventional dose rate (CONV) RT. Dosimetry in FLASH beams is challenging and complex as beam monitoring and proper dosimetry analysis remain uncertain and under investigation. Despite these limitations, clinical translation of FLASH RT has already begun. For translation of FLASH RT from the preclinical stage, it is critical that robust clinical workflows and dosimetry methods be confidently established to ensure patient safety. Here, we present the clinical workflow for the Yorkshire pig, an animal that resembles the body dimension, weight, and biology of a human patient, with the goal to establish standard operating procedures to ensure a safe and robust clinical translation in our upcoming phase I study in cutaneous tumors. The study determines feasibility and safety while finding incidence of dose-limiting toxicities and maximum tolerable dose for future Phase II trials.

MATERIALS/METHODS

All procedures were approved by the institutional animal care and use committee. 6 pigs (40-50 kg) were placed under general anesthesia and underwent CT imaging for radiation therapy simulation purposes. The skin was first shaven, and targets on the dorsolateral flanks were marked with tattoos and BBs for CT visualization. Vacloc immobilization was used to allow for reproducible setup on the treatment couch. A treatment planning model was established for treatment planning and dose evaluation purposes. CONV and FLASH single and fractionated dose regimens were prescribed to the 90% isodose line in a 9 MeV beam. Skin collimation and bolus minimized beam penumbra and increased skin dose. Treatment time and pulse repetition frequency were constant between all FLASH fields. Prescription levels were varied via dose per pulse. Calibration and verification of these settings were performed utilizing a multi-dosimeter method for verification in solid water. Output of the beam was verified on the day of the treatment using beam current transformers. This same multi-dosimeter method was used as in-vivo dosimetry on treatment day and compared to the dose verification ensure full dose was received.

RESULTS

Variation between the three dosimeter methods was found to be within 5% among all pigs within the study. The maximum percent difference between dose verification and dose delivery was 6%. Consideration must be taken in dosimeter readout error due to the surface of the pig skin. FLASH and CONV toxicity results are currently under evaluation and will be published upon completion of the study.

CONCLUSION

Establishing guidelines and protocols for electron FLASH clinical translation is important to instill confidence in patient safety with this new technique. This study has further optimized and developed dosimetry tools and setup to be used in future clinical trials.

Predictors of Low Anterior Resection Syndrome after Long-Course Chemoradiation for Locally Advanced Rectal Cancer

PURPOSE/OBJECTIVE(S)

Low anterior resection syndrome (LARS) describes disordered bowel function including tenesmus, frequent, clustered, incomplete, urgent or incontinent bowel movements. The impact of clinical and radiation dosimetric factors on LARS score is unknown. We aimed to evaluate the radiation plans for patients who received long course chemoradiation (LC-CRT) to identify potential dosimetric predictors of LARS.

MATERIALS/METHODS

We identified patients with rectal cancer treated with LC-CRT (50.4Gy in 28 fractions) at our institution from 2016-2020 who were alive and without disease. As a part of a larger patient-reported outcome survey, we obtained the Low Anterior Resection Syndrome Score (LARS) for patients without an ostomy at the time of the survey. We utilized clinical and dosimetric variables in a multivariate analysis including age at LC-CRT, body mass index, sex, distance of the tumor from the anal verge (AV), threatened mesorectal fascia (MRF) on staging imaging, T-stage, N-stage, receipt of surgery (vs non-operative management (NOM), radiation technique (3DCRT vs VMAT), mean dose and D0.03ccs for the anal canal (defined as 4cm from the anal verge) and D0.03cc, V30Gy and V45Gy for the small bowel loops. We then created a multiple linear regression model to predict LARS using P>.20 on univariate testing.

RESULTS

Of 110 patients treated with preoperative LC-CRT and who did not have an ostomy, 57 responded (51.8%). The median [interquartile range (IQR)] interval from completion of LC-CRT to survey completion was 38.4 months [26.3-48.9]. Thirty-four patients (60%) were men, the median [IQR] BMI was 28 [24-31.9], the median [IQR] distance of the tumor to the anal verge was 7cm [5-10], 40 (70%) had T3 tumors, 7 (12%) had T4 tumors, 45 (79%) were N+. Forty-one patients (72%) had surgery following LC-CRT, and 16 (28%) had non-operative management. 3D conformal technique was used for 47 (82%) and VMAT used for 10 patients (18%). The median [IQR] LARS score was 32 [24-38] with 35 patients (61%) classified as Major LARS (LARS score = 30-42). On multiple linear regression modeling (Table), only receipt of surgery significantly predicted for higher (worse) LARS score.

CONCLUSION

In our cohort, patients who received surgery after LC-CRT had a significantly higher LARS score. Of the dosimetric parameters tested, D0.03ccs was the best predictor and could potentially be significant with a larger number of patients. Further work is needed to improve bowel function and quality of life for patients treated with LC-CRT for rectal adenocarcinoma.

Assessment of the Spatial Bio-Distribution of NBTXR3 for Locally Advanced or Borderline-Resectable Pancreatic Ductal Adenocarcinoma (LAPC or BRPC) Patients Undergoing Radiation Therapy

PURPOSE/OBJECTIVE(S)

NBTXR3 is a novel radioenhancer composed of functionalized hafnium oxide nanoparticles that are injected directly into the tumor. An ongoing phase I trial is assessing the application of NBTXR3 in the treatment of locally-advanced or borderline-resectable pancreatic ductal adenocarcinoma, with the primary goal of determining the recommended NBTXR3 dose for a subsequent phase II trial. Using patients from the ongoing phase I trial, we evaluated the spatial bio-distribution of NBTXR3 in the pancreas as function of time and assessed if there is migration of the compound during radiation therapy.

MATERIALS/METHODS

Adult patients with LAPC or BRPC were enrolled. Analysis of 8 patients who underwent CT simulation at least 24 hours after receiving the NBTXR3 intratumoral injection in the pancreatic lesion under general anesthesia guided by an endoscopic ultrasound was conducted. Patients were simulated with and without iodinated intravenous contrast under breath hold, with 3mm CT slice thickness and 50-60cm FoV. A contrast-enhanced CT series was chosen for RT planning purposes. All patients were planned for a 15-fraction IMRT course using 6-MV beam energy, with 45Gy and 37.5Gy dose levels (using a simultaneous integrated boost technique) to gross primary tumor and microscopic disease/regional nodes, respectively. Daily image guidance included either cone-beam CT (CBCT, n = 1) or CT-on-Rails (CTOR, n = 7) and were fused to the planning CT images using Velocity, ver. 3.0.1. The NBTXR3 volume was determined by thresholding the images to 165 HU and 300 HU for CTOR and CBCT images, respectively. Bones, stents, and artifacts were manually removed from the NBTXR3 volume. The volumes for the NBTXR3 and the NBTXR3 overlapping with the GTV for each patient were individually fit to a linear model in R, ver. 4.1.3.

RESULTS

One patient from the CTOR cohort was excluded from analysis due to the small volume of NBTXR3 (0.02 cm3) compared to the rest of the cohort (0.716 - 6.917 cm3). The total volume of NBTXR3 in the CBCT images could not be analyzed due the substantial image artifacts, only the volume overlapping the GTV was calculated. There were no statistically significant changes (p > 0.1 Adj-R2 = 0.99) in the raw volume of NBTXR3 for the duration of the treatment in all CTOR patients. For the NBTXR3 volume overlapping with the GTV, five cases did not present with a volume change during the treatment (p > 0.1 Adj-R2 = 0.99), while one CTOR case had a reduction in volume of about 1.5%/day (p = 0.7), and the CBCT case had a reduction of 3%/day (p < 0.001).

CONCLUSION

The raw volume of NBTXR3 injected in the pancreas did not significantly change over the duration of the three weeks of treatment. We also did not observe significant changes in the NBTXR3 volume overlapping the GTV in most cases. The stability of NBTXR3 was demonstrated during RT.

Sexual Orientation and Gender Identity (SOGI) Data Collection: Opportunities to Advance Best Clinical Practices for LGBTQ+ Patients in Radiation Oncology

PURPOSE/OBJECTIVE(S)

A long-standing barrier to progress against health disparities is the lack of data regarding cancer risks, prevalence, treatment, and outcomes for sexual and gender minority (SGM) patients. Sexual orientation and gender identity (SOGI) data are not routinely collected by individual oncologists, cancer centers, or most non-federal hospital systems. Alarmingly high proportions of SGM patients report discrimination in healthcare or avoid routine care due to perceived lack of acceptance in the healthcare system. For these and other reasons, healthcare institutions must adopt practices that promote an inclusive environment for all patients including those self-identified from SGM groups. One strategy to achieve this aim is through SOGI data collection. The purpose of this study was to pilot new procedures and training for SOGI data collection, the aims of this project were to standardize the collection of SOGI data for all new patients referred to the Division of Radiation Oncology; promote clinical staff awareness of SGM health disparities and strategies for fostering an inclusive hospital environment; and to provide SGM patients and caregivers educational resources and support systems tailored to their needs.

MATERIALS/METHODS

We designed a Quality Improvement program for collecting SOGI data, which was approved by our institution's QIAB. Patient access specialists (PAS) were trained to collect SOGI data from newly registered patients and enter the data into the electronic health record. Radiation Oncology staff completed surveys before and after SOGI training to estimate its impact on the provision of patient care. A Fisher's exact test was utilized to evaluate associations between training and provider-reported outcomes.

RESULTS

Within a 3-week period starting in January 2023, two 1-hour interactive training sessions were offered to twenty-five PAS. Three 1-hour training sessions were offered to twenty-seven Radiation Oncology clinical staff. (1) Confidence for incorporating SOGI classifiers around patients improved from before training (52%, 13/25) to after training (100%, 17/17) among medical providers surveyed (odds ratio (OR) 32, 95% confidence interval (CI) 0.70-1493, p = 0.005). Use of SOGI data in clinical decision making increased from before training (9/25, 36%) to after training (100%, 17/17) among medical providers (OR 60.79, 95% CI 3.271-1130, p<0.0001). (2) A clinical pathway for SGM patients was developed to facilitate referral to our institution's SGM patient support group and distribution of patient education materials focused on sexual health.

CONCLUSION

Establishing standardized SOGI data collection can facilitate the provision of tailored resources and care that meets the needs of patients and staff in a large comprehensive cancer center. Specialized training for staff developed through this initiative helps foster an inclusive and welcoming environment that promotes the integration, visibility, and advancement of SGM cancer care at our institution.

Outcomes and after Hyperfractionated, Accelerated Reirradiation for Recurrent Anal Squamous Cell Carcinoma

PURPOSE/OBJECTIVE(S)

Abdominoperineal resection (APR) is the standard salvage treatment for recurrent or persistent squamous cell carcinoma of the anus (SCCA). However, reirradiation (reRT) can be used preoperatively or for those who are not candidates for surgery.

MATERIALS/METHODS

Using a single institutional database, patients were identified who underwent reRT for SCCA from 2003 to 2022. Response to reRT and outcomes after reRT were recorded. Variables analyzed included age at reRT, sex, reason for reRT (recurrent SCCA vs new SCCA after pelvic radiation for a different malignancy), interval between initial radiation and reRT, reRT dose, concurrent chemotherapy, receipt of APR and the presence of distant metastases at the time of reRT. Cox Proportional Hazard Model was used; multivariable analysis for all factors with a univariate P-value <0.1 on univariable analysis.

RESULTS

A total of 42 patients received reRT, which consisted of 1.5 Gray (Gy) twice daily fractions with ≥6-hour interval to a total dose ranging 30Gy to 54Gy (median [IQR] 39Gy [39-42Gy]. Thirty-eight patients (90.5%) received concurrent chemotherapy; most often with weekly cisplatin and 5-fluorouracil (N = 23, 54.8%). Median [IQR] follow-up after reRT was 11.4 months [4.9-40.8 months]. Median [IQR] initial radiation dose was 54Gy [54-58Gy], and median [IQR] interval between initial radiation and reRT was 3.6 years [2.1-6.0 years]. For 8 patients (19.1%), the initial radiation was given for a different pelvic malignancy prior to being diagnosed with SCCA. Four of these patients received brachytherapy alone or in conjunction with external beam. For the remaining 34 patients, the initial radiation was for SCCA and the reRT was for recurrent SCCA either in the anal canal (N = 23, 67.6%) or regional nodes (N = 11, 32.3%). Four patients (9.5%) had distant disease at the time of reRT. Eleven patients (26.2%) had planned APR after preoperative reRT; 1 patient had a pathologic complete response (pCR), 2 patients had a near pCR (<5% viable cancer). Twenty-nine patients (69.0%) were treated with reRT alone; 15 (51.7%) attained a clinical CR. Two patients (4.8%) were treated with palliative intent and response was not assessed. Median local recurrence free survival (LRFS) was 9.9 months; 2- and 3-year LRFS were both 41%. Median distant metastasis free survival (DMFS) was 11.8 months; 2- and 3-year DMFS were 38% and 34%, respectively. Median overall survival (OS) was 40.5 months; 2- and 3-year OS were 54% and 51%, respectively. On multivariable analysis, only the presence of distant disease at the time of reRT was significantly associated with worse LRFS (HR (95% CI) 4.14 (1.34-12.81); P = .014), worse DMFS (4.06 (1.37-12.06); P = .012) and worse OS (5.73 (1.57-20.9); P = .008).

CONCLUSION

ReRT is an option for patients presenting with either recurrent SCCA or new SCCA after prior pelvic radiation for a different malignancy. ReRT can be given prior to planned salvage APR or alone for patients who are not surgical candidates with an approximate 50% cCR rate.

Phase 1 Trial of SPECT-Guided Liver-Directed Ablative Radiotherapy for Patients with Low Functional Liver Volume

PURPOSE/OBJECTIVE(S)

Traditional liver dose constraints specify that a critical volume of 700 cc of non-tumor liver should be spared from receiving a hepatotoxic dose. We evaluated the safety of liver-directed ablative radiotherapy for patients with hepatocellular carcinoma (HCC), intrahepatic cholangiocarcinoma (iCCA), or liver metastases (LM) with Child-Pugh (CP) A5 liver function at baseline and with low functional liver volume as estimated by Tc-99m sulfur colloid single photon emission computed tomography (SPECT). We hypothesized that functional liver image guidance with SPECT would allow safe delivery of ablative radiotherapy in patients with limited liver volume.

MATERIALS/METHODS

A phase 1 trial with a 3+3 design was conducted to evaluate the safety of comprehensive ablative radiotherapy to the liver disease using escalating functional non-target liver radiation dose constraints. Eligibility criteria included (1) a diagnosis of HCC, iCCA, or LM, (2) prior treatment with irinotecan or oxaliplatin chemotherapy or liver resection, and (3) a minimum functional liver volume of 400 cc as estimated by SPECT using a threshold of 40% maximum intensity. Patients with CP >A5 liver function, prior liver-directed radiotherapy, or prior Yttrium-90 therapy were excluded. The prescription dose was 67.5-75 Gy in 15 fractions or 75-100 Gy in 25 fractions. The volumetric dose constraint for functional non-target liver receiving <24 Gy for 15 fractions or <27 Gy for 25 fractions was determined by the dose level of trial enrollment: level 0 was ≥400 cc and level +1 was ≥300 cc. A level -1 was included if needed. We used standard 15 and 25 fraction dose constraints for other organs at risk. The following dose limiting toxicities (DLTs) were assessed within 6-8 weeks of completing radiotherapy: Grade 3 hypoalbuminemia, increase in INR, increase in bilirubin, or ascites, or Grade 4 hepatic failure or any radiation-related toxicity.

RESULTS

Twelve patients enrolled between February 2016 and June 2022. The median (range) GTV was 36 (2-651) cc. The median CT anatomical non-tumor liver volume was 1584 (764-2699) cc, and the median SPECT functional liver volume was 1117 (570-1928) cc, with a Pearson correlation coefficient of 0.98 (p<0.001). The median non-target SPECT functional liver volume below the volumetric dose constraint was 684 (429-1244) cc. None of the 3 patients treated in dose level 0, and none of the 9 patients treated in dose level +1 experienced any DLTs. The 1-year in-treatment-field control rate was 55%, and 1-year overall survival was 71%.

CONCLUSION

Ablative radiotherapy can be safely delivered using functional SPECT image guidance, which enables sparing lower volumes of functional liver than traditionally accepted in patients with CP A5 liver function. Further evaluation with a phase 2 study is warranted.

Subacute Cutaneous Toxicity with Single-Fraction Electron FLASH RT in Yorkshire Swine

PURPOSE/OBJECTIVE(S)

Information regarding acute/subacute skin toxicity of electron FLASH radiation therapy (RT) is limited. We evaluated short-term safety of electron FLASH for human trials by investigating subacute toxicity compared to conventional dose-rate RT (CONV) in the Yorkshire pig, an animal model known to closely approximate human skin and routinely used for toxicity studies.

MATERIALS/METHODS

Two healthy 50 kg pigs underwent CT imaging for RT treatment planning with field visualization via BBs and tattoos on each dorsolateral flank. Each target received a single fraction of 20, 25 or 30 Gy with FLASH and CONV on opposing sides delivered using a dedicated mobile linear accelerator. FLASH dose rates ranged from 164-245 Gy/sec (12 pulses delivered over 0.122 sec) while the CONV dose rate was set at 0.18 Gy/sec. Doses were verified using thermo- and optically stimulated luminescent dosimeters, and Gafchromic films. We obtained baseline and weekly images up to 98 days post-RT (D98) for blinded toxicity grading by 3 expert radiation oncologists using the modified RTOG radiation dermatitis (RD) scale. We measured erythema and pigmentation indices on those timepoints using a handheld spectrophotometer. We also obtained punch biopsies of targets and non-irradiated controls on D10 and D30 for RNA sequencing and two 6-marker multiplex immunofluorescence analyses of inflammation, immune response, and fibrosis. FLASH and CONV data were compared using repeated measures ANOVA and transcriptomic analyses using DESeq2.

RESULTS

All RT targets developed peak median grade 4 (ulceration, hemorrhage, or necrosis) RD by D84 regardless of FLASH or CONV delivery. However, FLASH targets developed peak RD later than CONV targets after 20 Gy (D84 vs D63), 25 Gy (D84 vs D49) and 30 Gy (D63 vs D42). FLASH induced qualitatively lower mean pigmentation and erythema indices than CONV for all 3 doses. Similarly, peak mean pigmentation indices occurred later with FLASH vs CONV for 20 Gy (D84 vs D63), 25 Gy (D84 vs D49) and 30 Gy (D77 vs D63). However, peak mean erythema indices occurred on the same day for FLASH and CONV (D63 for 20 Gy and D42 for 25 and 30 Gy). Transcriptomic analyses revealed significantly upregulated signals for wound healing (including TGF-beta, cell adhesion and extracellular matrix receptor interaction) and leukocyte infiltration with 20 Gy CONV mostly by D10, while FLASH upregulated those pathways only after 25 or 30 Gy, or by D30, or never at all. Preliminary immunofluorescence data showed FLASH may induce less T cell infiltrate and TGF-beta-expressing macrophages than CONV.

CONCLUSION

Single-fraction electron FLASH resulted in delayed onsets of both subacute cutaneous toxicity and wound healing with leukocytic infiltration signaling than dose-matched CONV based on both subjective and objective metrics of skin injury. Our findings suggest further investigations of optimal dose of electron FLASH for safe clinical translation is warranted, and we have a dose-finding study currently underway.

Definitive Liver Radiotherapy for Intrahepatic Cholangiocarcinoma with Extrahepatic Metastases

Introduction

Tumor-related liver failure (TRLF) is the most common cause of death in patients with intrahepatic cholangiocarcinoma (ICC). Though we previously showed that liver radiotherapy (L-RT) for locally advanced ICC is associated with less frequent TRLF and longer overall survival (OS), the role of L-RT for patients with extrahepatic metastatic disease (M1) remains undefined. We sought to compare outcomes for M1 ICC patients treated with and without L-RT.

Methods

We reviewed ICC patients that found to have M1 disease at initial diagnosis at a single institution between 2010 and 2021 who received L-RT, matching them with an institutional cohort by propensity score and a National Cancer Database (NCDB) cohort by frequency technique. The median biologically effective dose was 97.5 Gy (interquartile range 80.5-97.9 Gy) for L-RT. Patients treated with other local therapies or supportive care alone were excluded. We analyzed survival with Cox proportional hazard modeling.

Results

We identified 61 patients who received L-RT and 220 who received chemotherapy alone. At median follow-up of 11 months after diagnosis, median OS was 9 months (95% confidence interval [CI] 8-11) and 21 months (CI: 17-26) for patients receiving chemotherapy alone and L-RT, respectively. TRLF was the cause of death more often in the patients who received chemotherapy alone compared to those who received L-RT (82% vs. 47%; p = 0.001). On multivariable propensity score-matched analysis, associations with lower risk of death included duration of upfront chemotherapy (hazard ratio [HR] 0.82; p = 0.005) and receipt of L-RT (HR: 0.40; p = 0.002). The median OS from diagnosis for NCDB chemotherapy alone cohort was shorter than that of the institutional L-RT cohort (9 vs. 22 months; p < 0.001).

Conclusion

For M1 ICC, L-RT associated with a lower rate of death due to TRLF and longer OS versus those treated with chemotherapy alone. Prospective studies of L-RT in this setting are warranted.

Independent Reproduction of the FLASH Effect on the Gastrointestinal Tract: A Multi-Institutional Comparative Study

FLASH radiation therapy (RT) is a promising new paradigm in radiation oncology. However, a major question that remains is the robustness and reproducibility of the FLASH effect when different irradiators are used on animals or patients with different genetic backgrounds, diets, and microbiomes, all of which can influence the effects of radiation on normal tissues. To address questions of rigor and reproducibility across different centers, we analyzed independent data sets from The University of Texas MD Anderson Cancer Center and from Lausanne University (CHUV). Both centers investigated acute effects after total abdominal irradiation to C57BL/6 animals delivered by the FLASH Mobetron system. The two centers used similar beam parameters but otherwise conducted the studies independently. The FLASH-enabled animal survival and intestinal crypt regeneration after irradiation were comparable between the two centers. These findings, together with previously published data using a converted linear accelerator, show that a robust and reproducible FLASH effect can be induced as long as the same set of irradiation parameters are used.

Differential Spatial Gene and Protein Expression Associated with Recurrence Following Chemoradiation for Localized Anal Squamous Cell Cancer

The identification of transcriptomic and protein biomarkers prognosticating recurrence risk after chemoradiation of localized squamous cell carcinoma of the anus (SCCA) has been limited by a lack of available fresh tissue at initial presentation. We analyzed archival FFPE SCCA specimens from pretreatment biopsies prior to chemoradiation for protein and RNA biomarkers from patients with localized SCCA who recurred (N = 23) and who did not recur (N = 25). Tumor cells and the tumor microenvironment (TME) were analyzed separately to identify biomarkers with significantly different expression between the recurrent and non-recurrent groups. Recurrent patients had higher mean protein expression of FoxP3, MAPK-activation markers (BRAF, p38-MAPK) and PI3K/Akt activation (phospho-Akt) within the tumor regions. The TME was characterized by the higher protein expression of immune checkpoint biomarkers such as PD-1, OX40L and LAG3. For patients with recurrent SCCA, the higher mean protein expression of fibronectin was observed in the tumor and TME compartments. No significant differences in RNA expression were observed. The higher baseline expression of immune checkpoint biomarkers, together with markers of MAPK and PI3K/Akt signaling, are associated with recurrence following chemoradiation for patients with localized SCCA. These data provide a rationale towards the application of immune-based therapeutic strategies to improve curative-intent outcomes beyond conventional therapies for patients with SCCA.

Physician Perspectives on Telemedicine in Radiation Oncology

Purpose

Telemedicine enthusiasm and uptake in radiation oncology rapidly increased during the COVID-19 pandemic, but it is unclear if and how telemedicine should be used after the COVID-19 public health emergency ends is unclear. Herein, we report on our institution's provider experience after the mature adoption of telemedicine.

Methods and Materials

We distributed a survey to all radiation oncology attending physicians at our institution in October 2021 to assess satisfaction, facilitators, and barriers to telemedicine implementation. We performed quantitative and qualitative analyses to characterize satisfaction and identify influencing factors whether telemedicine is employed. We calculated the average proportion of visits that providers expected to be appropriately performed with telemedicine for each disease site and visit type.

Results

A total of 60 of the 82 eligible radiation oncologists (73%) responded to the survey, of whom 78% were satisfied with telemedicine in the radiation oncology department and 83% wished to continue offering video visits after the COVID-19 public health emergency ends. Common patient factors influencing whether physicians offer telemedicine include the patient's travel burden, patient preferences, and whether a physical examination is required. Approximately 20% of new consultations and 50% of weekly management visits were estimated to be appropriate for telemedicine. The central nervous system/pediatrics and thoracic faculty considered telemedicine appropriate for the greatest proportion of new consultations, and 93% of respondents felt comfortable determining whether telemedicine was appropriate.

Conclusions

Surveyed radiation oncologists were satisfied with telemedicine in their practice, and wished to continue offering video visits in the future. Our data suggest that payers should continue to support this patient-centered technology.

Validation of a Resectability Scoring System for Prediction of Pancreatic Adenocarcinoma Surgical Outcomes

BACKGROUND

The most used pancreatic cancer (PC) resectability criteria are descriptive in nature or based solely on dichotomous degree of involvement (< 180° or > 180°) of vessels, which allows for a high degree of subjectivity and inconsistency.

METHODS

Radiographic measurements of the circumferential degree and length of tumor contact with major peripancreatic vessels were retrospectively obtained from pre-treatment multi-detector computed tomography (MDCT) images from PC patients treated between 2001 and 2015 at two large academic institutions. Arterial and venous scores were calculated for each patient, then tested for a correlation with tumor resection and R0 resection.

RESULTS

The analysis included 466 patients. Arterial and venous scores were highly predictive of resection and R0 resection in both the training (n = 294) and validation (n = 172) cohorts. A recursive partitioning tree based on arterial and venous score cutoffs developed with the training cohort was able to stratify patients of the validation cohort into discrete groups with distinct resectability probabilities. A refined recursive partitioning tree composed of three resectability groups was generated, with probabilities of resection and R0 resection of respectively 94 and 73% for group A, 61 and 35% for group B, and 4 and 2% for group C. This resectability scoring system (RSS) was highly prognostic, predicting median overall survival times of 27, 18.9, and 13.5 months respectively for patients in RSS groups A, B, and C (p < 0.001).

CONCLUSIONS

The proposed RSS was highly predictive of resection, R0 resection, and prognosis for patients with PC when tested against an external dataset.

Patient-reported Bowel Function and Bowel-related Quality of Life After Pelvic Radiation for Rectal Adenocarcinoma: The Impact of Radiation Fractionation and Surgical Resection

INTRODUCTION

Multimodality treatment for locally advanced rectal cancer (LARC) can include long-course radiotherapy (LCRT) or short course radiotherapy (SCRT). Nonoperative management is increasingly pursued for those achieving a complete clinical response. Data regarding long-term function and quality-of-life (QOL) are limited.

METHODS

Patients with LARC treated with radiotherapy from 2016 to 2020 completed the Functional Assessment of Cancer Therapy- General (FACT-G7), the Low Anterior Resection Syndrome Score (LARS) and the Fecal Incontinence QOL Scale (FIQOL). Univariate and multivariable linear regression analyses identified associations between clinical variables including radiation fractionation and the use of surgery versus non-operative management.

RESULTS

Of 204 patients surveyed, 124 (60.8%) responded. Median (interquartile range) time from radiation to survey completion was 30.1 (18.3-43) months. Seventy-nine (63.7%) respondents received LCRT, and 45 (36.3%) received SCRT; 101 (81.5%) respondents underwent surgery, and 23 (18.5%) pursued nonoperative management. There were no differences in LARS, FIQoL or FACT-G7 between patients receiving LCRT versus SCRT. On multivariable analysis, only nonoperative management was associated with lower LARS score signifying less bowel dysfunction. Nonoperative management and female sex were associated with a higher FIQoL score signifying less disruption and distress from fecal incontinence issues. Finally, lower BMI at the time of radiation, female sex, and higher FIQoL score were associated with higher FACT-G7 scores signifying better overall QOL.

CONCLUSIONS

These results suggest long-term patient-reported bowel function and QOL may be similar for individuals receiving SCRT and LCRT for the treatment of LARC, but nonoperative management may lead to improved bowel function and QOL.

Spatially Resolved Single-Cell Assessment of Pancreatic Cancer Expression Subtypes Reveals Co-expressor Phenotypes and Extensive Intratumoral Heterogeneity

Pancreatic ductal adenocarcinoma (PDAC) has been classified into classical and basal-like transcriptional subtypes by bulk RNA measurements. However, recent work has uncovered greater complexity to transcriptional subtypes than was initially appreciated using bulk RNA expression profiling. To provide a deeper understanding of PDAC subtypes, we developed a multiplex immunofluorescence (mIF) pipeline that quantifies protein expression of six PDAC subtype markers (CLDN18.2, TFF1, GATA6, KRT17, KRT5, and S100A2) and permits spatially resolved, single-cell interrogation of pancreatic tumors from resection specimens and core needle biopsies. Both primary and metastatic tumors displayed striking intratumoral subtype heterogeneity that was associated with patient outcomes, existed at the scale of individual glands, and was significantly reduced in patient-derived organoid cultures. Tumor cells co-expressing classical and basal markers were present in > 90% of tumors, existed on a basal-classical polarization continuum, and were enriched in tumors containing a greater admixture of basal and classical cell populations. Cell-cell neighbor analyses within tumor glands further suggested that co-expressor cells may represent an intermediate state between expression subtype poles. The extensive intratumoral heterogeneity identified through this clinically applicable mIF pipeline may inform prognosis and treatment selection for patients with PDAC.

SIGNIFICANCE

A high-throughput pipeline using multiplex immunofluorescence in pancreatic cancer reveals striking expression subtype intratumoral heterogeneity with implications for therapy selection and identifies co-expressor cells that may serve as intermediates during subtype switching.

Dose Escalation for Pancreas SBRT: Potential and Limitations of using Daily Online Adaptive Radiation Therapy and an Iterative Isotoxicity Automated Planning Approach

Purpose

To determine the dosimetric limitations of daily online adaptive pancreas stereotactic body radiation treatment by using an automated dose escalation approach.

Methods and Materials

We collected 108 planning and daily computed tomography (CT) scans from 18 patients (18 patients × 6 CT scans) who received 5-fraction pancreas stereotactic body radiation treatment at MD Anderson Cancer Center. Dose metrics from the original non-dose-escalated clinical plan (non-DE), the dose-escalated plan created on the original planning CT (DE-ORI), and the dose-escalated plan created on daily adaptive radiation therapy CT (DE-ART) were analyzed. We developed a dose-escalation planning algorithm within the radiation treatment planning system to automate the dose-escalation planning process for efficiency and consistency. In this algorithm, the prescription dose of the dose-escalation plan was escalated before violating any organ-at-risk (OAR) dose constraint. Dose metrics for 3 targets (gross target volume [GTV], tumor vessel interface [TVI], and dose-escalated planning target volume [DE-PTV]) and 9 OARs (duodenum, large bowel, small bowel, stomach, spinal cord, kidneys, liver, and skin) for the 3 plans were compared. Furthermore, we evaluated the effectiveness of the online adaptive dose-escalation planning process by quantifying the effect of the interfractional dose distribution variations among the DE-ART plans.

Results

The median D_95% dose to the GTV/TVI/DE-PTV was 33.1/36.2/32.4 Gy, 48.5/50.9/40.4 Gy, and 53.7/58.2/44.8 Gy for non-DE, DE-ORI, and DE-ART, respectively. Most OAR dose constraints were not violated for the non-DE and DE-ART plans, while OAR constraints were violated for the majority of the DE-ORI patients due to interfractional motion and lack of adaptation. The maximum difference per fraction in D_95%, due to interfractional motion, was 2.5 ± 2.7 Gy, 3.0 ± 2.9 Gy, and 2.0 ± 1.8 Gy for the TVI, GTV, and DE-PTV, respectively.

Conclusions

Most patients require daily adaptation of the radiation planning process to maximally escalate delivered dose to the pancreatic tumor without exceeding OAR constraints. Using our automated approach, patients can receive higher target dose than standard of care without violating OAR constraints.

Dose-escalated pancreas radiotherapy for unresected pancreatic adenocarcinoma: Patterns of care and survival in the United States

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Background: Randomized trials have not shown an overall survival (OS) benefit to adding radiotherapy (RT) to chemotherapy for patients with locally advanced pancreatic adenocarcinoma (LAPC). However, trials such as LAP07 did not incorporate escalated-dose RT (EDR), which may confer longer survival. The adoption of EDR across the United States and associated outcomes are unknown. Methods: We queried the National Cancer Data Base for non-surgically managed patients with LAPC diagnosed between 2004 and 2019. RT with biologically effective doses (BED10) > 70 and ≤ 200 Gy were labeled EDR and conventional-dose RT (CDR) for 39-70 Gy doses. Associations with receipt of EDR and with OS were identified using multivariate analysis (MVA) logistic and Cox regressions, respectively. Bonferroni corrections were applied. Cochran-Armitage and Mann-Kendall trend tests were performed to assess trends in use of RT. Results: Of 64,303 patients, the most common treatments were chemotherapy alone (CT) (71%), chemoradiation (CRT) (27%), and pancreas RT alone (2%). 18,970 patients received pancreas RT, of which 91% was CDR (median dose 50.4 Gy; median 28 fractions) and 9% was EDR (50 Gy; 5 fractions). Use of pancreas RT increased from 14% in 2004 to a peak of 18% in 2010, decreased to a nadir of 13% in 2016, and subsequently increased to 15% by 2019 ( Ptrend < 0.001). EDR use increased from 7% in 2004 to 22% in 2019 ( Ptrend < 0.0001). Median BED10 increased from 53 to 59 Gy ( Ptrend< 0.001). Of patients receiving pancreas RT, use of intensity-modulated RT (IMRT) and stereotactic body RT (SBRT) respectively increased from 25% and 2% in 2004 to 60% and 27% in 2019, while use of 3-D conformal RT (3D-CRT) decreased from 64% to 9% ( Ptrend < 0.02 for all comparisons). On MVA logistic regression, primary tumor location in the body/tail vs. head (aOR 1.22, 95% CI 1.07-1.40; P = 0.003) associated with greater EDR receipt, whereas T3-4 vs. T2 disease (aOR 0.81, CI 0.71-0.92; P = 0.002) associated with lesser receipt. At a median follow up of 59.1 months (CI 57.5-61.0), median OS estimates for CDR and EDR were 10.2 months (CI 10.1-10.3) and 13.3 months (CI 13.2-13.5; P < 0.0001), respectively. On MVA Cox regression, N1 vs. N0 disease (HR 1.08, CI 1.06-1.10; P < 0.001) correlated with higher risk of death, whereas CRT vs. CT (HR 0.83, CI 0.81-0.85; P < 0.001) correlated with lower risk of death. Subset MVA of 14,634 CRT patients correlated higher RT dose—as both a categorical variable (EDR vs. CDR; HR 0.84, CI 0.79-0.90; P < 0.001) and continuous variable (BED10; HR 0.994, CI 0.992-0.995; P < 0.001)—with lower risk of death. Conclusions: Fewer than 1 in 6 patients with unresected LAPC received pancreas RT, despite a nominal increase in utilization in recent years. Although retrospective, these NCDB data suggest longer OS with the addition of RT for unresected LAPC, suggesting continued unmet need. EDR is associated with longer survival vs. CDR.

Implementation and Assessment of an Informal Virtual Elective for Medical Student Radiation Oncology Exploration During the COVID19 Pandemic: a Brief Report

Subspecialty exposure during medical school can be limited. Moreover, the COVID19 pandemic prevented most onsite elective medical student (MS) rotations during 2020. Therefore, we sought to create and assess the efficacy of an informal virtual elective (IVE) for MSs to explore radiation oncology (RO) at our institution. We created IVE activities including invitations to resident didactics, a faculty lecture series, and interactive virtual events with residents and faculty. MSs were offered RO resident and faculty mentors and the opportunity to deliver a lecture. Pre- and post-IVE evaluation surveys were sent to 27 4th year MSs. Surveys utilized importance ordering (1=most important; reported as median (interquartile range), free response, and Likert-type questions (5 = extremely, 1=not at all). Our IVE, held from July to October 2020, had a median of 11 students (range 7-18) attend each activity. Pre- and post-IVE surveys were completed by 22/27 (81%) and 20/27 (74%) MSs, respectively. In pre-IVE, MSs reported participating in the IVE for faculty/resident interaction (1.5 [1, 2]), networking (3 [2, 3]), and learning (4 [3-5]). In post-IVE, MSs reported benefit from faculty mentors (5 [4, 5]), delivering a presentation (5 [3-5]), and faculty lectures (4.5 [4, 5]). In post-IVE, MSs preferred a full onsite away elective (16, 80%) over an official virtual elective (1, 5%) or IVE (3, 15%). Overall, MSs reported that the IVE provided an adequate introduction to RO at our institution (4 [4, 5]). Alternative virtual elective experiences allow MSs to informally evaluate medical subspecialties and could be offered even if formal elective opportunities are available.

Brain Metastases from Biliary Tract Cancer: Case Series and Clinicogenomic Analysis

BACKGROUND

Limited data from small series have suggested that brain metastases from biliary tract cancers (BrM-BTC) affect ≤2% of patients with BTC. We sought to review our experience with patients with BrM-BTC and to identify associations of tumor-related molecular alterations with outcomes.

MATERIALS AND METHODS

A retrospective review of patients with BTC seen at a tertiary referral center from 2005 to 2021 was performed; patients with BrM-BTC were identified, and clinical and molecular data were collected.

RESULTS

Twenty-one of 823 patients with BTC (2.6%) developed BrM. For patients with BrM-BTC, median follow-up time was 27.9 months after primary BTC diagnosis and 3.1 months after BrM diagnosis. Median time from primary diagnosis to diagnosis of BrM was 14.4 [range, 1.1-66.0] months. Median overall survival (OS) from primary diagnosis was 31.5 [2.9-99.8] months and median OS from BrM diagnosis was 4.2 [0.2-33.8] months. Patients who underwent BrM-directed therapy trended toward longer OS following BrM diagnosis than patients receiving supportive care only (median 6.5 vs 0.8 months, P = .060). The BrM-BTC cohort was enriched for BRAF (30%), PIK3CA (25%), and GNAS (20%) mutations. patients with BrM-BTC with BRAF mutations trended toward longer OS following BrM diagnosis (median 13.1 vs 4.2 months, P = .131).

CONCLUSION

This is the largest series of patients with BrM-BTC to date and provides molecular characterization of this rare subgroup of patients with BTC. Patients with BrM-BTC may be more likely to have BRAF mutations. With advances in targeted therapy for patients with BTC with actionable mutations, continued examination of shifting patterns of failure, with emphasis on BrM, is warranted.

Using patient flow analysis with real-time patient tracking to optimize radiation oncology consultation visits

PURPOSE

Clinical efficiency is a key component of the value-based care model and a driver of patient satisfaction. The purpose of this study was to identify and address inefficiencies at a high-volume radiation oncology clinic.

METHODS AND MATERIALS

Patient flow analysis (PFA) was used to create process maps and optimize the workflow of consultation visits in a gastrointestinal radiation oncology clinic at a large academic cancer center. Metrics such as cycle times, waiting times, and rooming times were assessed by using a real-time patient status function in the electronic medical record for 556 consults and compared between before vs after implementation of the PFA recommendations.

RESULTS

The initial PFA revealed four inefficiencies: (1) protracted rooming time, (2) inefficient communications, (3) duplicated tasks, and (4) ambiguous clinical roles. We analyzed 485 consult-visits before the PFA and 71 after the PFA. The PFA recommendations led to reductions in overall median cycle time by 21% (91 min vs 72 min, p < 0.001), in cumulative waiting times by 64% (45 min vs 16 min; p < 0.001), which included waiting room time (14 min vs 5 min; p < 0.001) and wait for physician (20 min vs. 6 min; p < 0.001). Slightly less than one-quarter (22%) of consult visits before the PFA lasted > 2 h vs. 0% after implementation of the recommendations (p < 0.001). Similarly, the proportion of visits requiring < 1 h was 16% before PFA vs 34% afterward (p < 0.001).

CONCLUSIONS

PFA can be used to identify clinical inefficiencies and optimize workflows in radiation oncology consultation clinics, and implementing their findings can significantly improve cycle times and waiting times. Potential downstream effects of these interventions include improved patient experience, decreased staff burnout, financial savings, and opportunities for expanding clinical capacity.

Neoadjuvant Chemotherapy Is Associated with Altered Immune Cell Infiltration and an Anti-Tumorigenic Microenvironment in Resected Pancreatic Cancer

PURPOSE

Neoadjuvant chemotherapy is increasingly administered to patients with resectable or borderline resectable pancreatic ductal adenocarcinoma (PDAC), yet its impact on the tumor immune microenvironment is incompletely understood.

EXPERIMENTAL

DESIGN

We employed quantitative, spatially resolved multiplex immunofluorescence and digital image analysis to identify T-cell subpopulations, macrophage polarization states, and myeloid cell subpopulations in a multi-institution cohort of up-front resected primary tumors (n = 299) and in a comparative set of resected tumors after FOLFIRINOX-based neoadjuvant therapy (n = 36) or up-front surgery (n = 30). Multivariable-adjusted Cox proportional hazards models were used to evaluate associations between the immune microenvironment and patient outcomes.

RESULTS

In the multi-institutional resection cohort, immune cells exhibited substantial heterogeneity across patient tumors and were located predominantly in stromal regions. Unsupervised clustering using immune cell densities identified four main patterns of immune cell infiltration. One pattern, seen in 20% of tumors and characterized by abundant T cells (T cell-rich) and a paucity of immunosuppressive granulocytes and macrophages, was associated with improved patient survival. Neoadjuvant chemotherapy was associated with a higher CD8:CD4 ratio, greater M1:M2-polarized macrophage ratio, and reduced CD15+ARG1+ immunosuppressive granulocyte density. Within neoadjuvant-treated tumors, 72% showed a T cell-rich pattern with low immunosuppressive granulocytes and macrophages. M1-polarized macrophages were located closer to tumor cells after neoadjuvant chemotherapy, and colocalization of M1-polarized macrophages and tumor cells was associated with greater tumor pathologic response and improved patient survival.

CONCLUSIONS

Neoadjuvant chemotherapy with FOLFIRINOX shifts the PDAC immune microenvironment toward an anti-tumorigenic state associated with improved patient survival.

Nab-Paclitaxel, Capecitabine, and Radiation Therapy After Induction Chemotherapy in Treating Patients With Locally Advanced and Borderline Resectable Pancreatic Cancer: Phase 1 Trial and Imaging-based Biomarker Validation

PURPOSE

Effective consolidative chemoradiation (CRT) regimens are lacking. In this phase 1 trial, we evaluated the safety and efficacy of nab-paclitaxel, capecitabine, and radiation therapy after induction chemotherapy in patients with locally advanced and borderline-resectable pancreatic cancer (LAPC and BRPC). Also, we evaluated a computed tomography (CT)-based biomarker of response.

METHODS AND MATERIALS

Eligible patients had pathologically confirmed pancreatic ductal adenocarcinoma, underwent computed tomography-imaging, received a diagnosis of LAPC or BRPC, and received induction chemotherapy. Standard 3 + 3 study design was used, with 3 escalating nab-paclitaxel dose levels (50, 75, and 100 mg/m²) with concurrent capecitabine and RT in cohort sizes of 3 starting at the lowest dose. Dose limiting toxicity was defined as grade 3 or higher toxicity. Patients were restaged 4 to 6 weeks post-CRT completion, and surgical resection was offered to those with stable/responsive disease. We scored the tumor interface response (IR) postchemotherapy and post-CRT into type I (remained/became more defined) and type II (became less defined). Overall survival (OS) and progression-free survival (PFS) from time of CRT were estimated using Kaplan-Meier method. P ≤ .05 was considered significant.

RESULTS

Twenty-three patients started and finished on protocol (LAPC = 14, BRPC = 9). No grade 3 and 4 toxicities were reported in level 1 (n = 3) or level 2 (n = 3) initial groups. Two patients in the initial level 3 group developed dose limiting toxicity, establishing level 2 dose as the maximal tolerated dose. Level 2 group was expanded for additional 15 patients (for a total of 23 on trial), 5 of whom developed grade 3 toxicities. Seven patients underwent surgical resection. Median OS and PFS were 21.2 and 8.1 months, respectively. Type I IR was associated with better OS (P = .004) and PFS (P = .03) compared with type II IR.

CONCLUSIONS

We established the maximum tolerated dose for nab-paclitaxel in a consolidative CRT regimen for pancreatic ductal adenocarcinoma. Preliminary efficacy results warrant phase 2 trial evaluation. IR may be used for personalized treatment.

Optimizing outpatient oncology consult workflow using time-driven activity-based costing: Efficiency and financial impacts

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Background: Clinical efficiency is a key component of value-based healthcare, patient satisfaction, staff burnout, and institutional operational capacity. The objective of this study was to identify clinic inefficiencies using time driven activity-based costing (TDABC) and evaluate the implementation of a new clinical workflow in high volume, outpatient radiation oncology clinics. Methods: We conducted an IRB-approved quality improvement study in the Gastrointestinal (GI), Genitourinary (GU), and Thoracic Radiation (TRO) Oncology departments at a large academic cancer center and four additional network sites (HALs). TDABC methodology was used to create process maps and optimize consult workflow. Patient encounter metrics were captured utilizing a real-time status function in the electronic medical record (Epic Systems). Anonymous patient satisfaction telephone surveys were administered to patients at the HALs. Hourly wages were determined based on 2021 U.S. Bureau of Labor Statistics. Pre- vs post-implementation metrics were compared using the Mann-Whitney U test. Results: Consult data for 1328 patients pre-intervention and 1234 post-intervention across all sections was included. Median overall cycle time was reduced by 21% in GI (19 min, p < 0.001), 18% in GU (16 min, p < 0.001), and 12% in HALs (9 min, p < 0.001). The median interval between rooming and being seen by the attending physician decreased by 13% in GI (7 min, p < 0.001), 16% in GU (9 min, p < 0.001), 21% in TRO (10 min, p < 0.001), and 9% in HALS (4 min, p < 0.005). For each consult, there was a median financial savings of $29 for GI, $24 for GU, $5 for TRO, and $14 for HALs per consult. From patient satisfaction surveys (95/177), 99% of patients reported their providers spent adequate time with them, 85% reported their appointment began on time, and 91% reported being seen by a care provider in a timely manner. Conclusions: TDABC is a successful method to identify opportunities to improve clinical efficiency. Implementing workflow changes based upon these findings led to substantial reduction in overall encounter cycle times and patient wait times across multiple departments. Furthermore, patient satisfaction was high and there were significant financial savings with the new workflow. These findings may also have implications for reducing staff burnout and expanding clinical capacity across the magnitude of clinical enterprise.[Table: see text]

Developing high-affinity decoy receptors to treat multiple myeloma and diffuse large B cell lymphoma

Disease relapse and treatment-induced immunotoxicity pose significant clinical challenges for patients with hematological cancers. Here, we reveal distinctive requirements for neutralizing TNF receptor ligands APRIL and BAFF and their receptor activity in MM and DLBCL, impacting protein translation and production in MM cells and modulating the translation efficiency of the ATM interactor (ATMIN/ACSIZ). Therapeutically, we investigated the use of BCMA decoy receptor (sBCMA-Fc) as an inhibitor of APRIL and BAFF. While wild-type sBCMA-Fc effectively blocked APRIL signaling in MM, it lacked activity in DLBCL due to its weak BAFF binding. To expand the therapeutic utility of sBCMA-Fc, we engineered an affinity-enhanced mutant sBCMA-Fc fusion molecule (sBCMA-Fc V3) 4- and 500-fold stronger in binding to APRIL and BAFF, respectively. The mutant sBCMA-Fc V3 clone significantly enhanced antitumor activity against both MM and DLBCL. Importantly, we also demonstrated an adequate toxicity profile and on-target mechanism of action in nonhuman primate studies.

Mass Transport Model of Radiation Response: Calibration and Application to Chemoradiation for Pancreatic Cancer

PURPOSE

The benefit of radiation therapy for pancreatic ductal adenocarcinoma (PDAC) remains unclear. We hypothesized that a new mechanistic mathematical model of chemotherapy and radiation response could predict clinical outcomes a priori, using a previously described baseline measurement of perfusion from computed tomography scans, normalized area under the enhancement curve (nAUC).

METHODS AND MATERIALS

We simplified an existing mass transport model that predicted cancer cell death by replacing previously unknown variables with averaged direct measurements from randomly selected pathologic sections of untreated PDAC. This allowed using nAUC as the sole model input to approximate tumor perfusion. We then compared the predicted cancer cell death to the actual cell death measured from corresponding resected tumors treated with neoadjuvant chemoradiation in a calibration cohort (n = 80) and prospective cohort (n = 25). After calibration, we applied the model to 2 separate cohorts for pathologic and clinical associations: targeted therapy cohort (n = 101), cetuximab/bevacizumab + radiosensitizing chemotherapy, and standard chemoradiation cohort (n = 81), radiosensitizing chemotherapy to 50.4 Gy in 28 fractions.

RESULTS

We established the relationship between pretreatment computed v nAUC to pathologically verified blood volume fraction of the tumor (r = 0.65; P = .009) and fractional tumor cell death (r = 0.97-0.99; P < .0001) in the calibration and prospective cohorts. On multivariate analyses, accounting for traditional covariates, nAUC independently associated with overall survival in all cohorts (mean hazard ratios, 0.14-0.31). Receiver operator characteristic analyses revealed discrimination of good and bad prognostic groups in the cohorts with area under the curve values of 0.64 to 0.71.

CONCLUSIONS

This work presents a new mathematical modeling approach to predict clinical response from chemotherapy and radiation for PDAC. Our findings indicate that oxygen/drug diffusion strongly influences clinical responses and that nAUC is a potential tool to select patients with PDAC for radiation therapy.

Adaptation and dosimetric commissioning of a synchrotron-based proton beamline for FLASH experiments

Objective. Irradiation with ultra-high dose rates (>40 Gy s−1), also known as FLASH irradiation, has the potential to shift the paradigm of radiation therapy because of its reduced toxicity to normal tissues compared to that of conventional irradiations. The goal of this study was to (1) achieve FLASH irradiation conditions suitable for pre-clinical i n vitro and in vivo biology experiments using our synchrotron-based proton beamline and (2) commission the FLASH irradiation conditions achieved. Approach. To achieve these suitable FLASH conditions, we made a series of adaptations to our proton beamline, including modifying the spill length and size of accelerating cycles, repurposing the reference monitor for dose control, and expanding the field size with a custom double-scattering system. We performed the dosimetric commissioning with measurements using an Advanced Markus chamber and EBT-XD films as well as with Monte Carlo simulations. Main results. Through adaptations, we have successfully achieved FLASH irradiation conditions, with an average dose rate of up to 375 Gy s−1. The Advanced Markus chamber was shown to be appropriate for absolute dose calibration under our FLASH conditions with a recombination factor ranging from 1.002 to 1.006 because of the continuous nature of our synchrotron-based proton delivery within a spill. Additionally, the absolute dose measured using the Advanced Markus chamber and EBT-XD films agreed well, with average and maximum differences of 0.32% and 1.63%, respectively. We also performed a comprehensive temporal analysis for FLASH spills produced by our system, which helped us identify a unique relationship between the average dose rate and the dose in our FLASH irradiation. Significance. We have established a synchrotron-based proton FLASH irradiation platform with accurate and precise dosimetry that is suitable for pre-clinical biology experiments. The unique time structure of the FLASH irradiation produced by our synchrotron-based system may shed new light onto the mechanism behind the FLASH effect.

Health Care Resource Utilization for Esophageal Cancer Using Proton versus Photon Radiation Therapy

Purpose

In patients treated with chemoradiation for esophageal cancer (EC), randomized trial data demonstrate that proton beam therapy (PBT) reduces toxicities and postoperative complications (POCs) compared with intensity-modulated radiation therapy (IMRT). However, whether radiation therapy modality affects postoperative health care resource utilization remains unknown.

Materials and Methods

We examined 287 patients with EC who received chemoradiation (prescribed 50.4 Gy/GyE) followed by esophagectomy, including a real-world observational cohort of 237 consecutive patients treated from 2007 to 2013 with PBT (n = 81) versus IMRT (n = 156); and an independent, contemporary comparison cohort of 50 patients from a randomized trial treated from 2012 to 2019 with PBT (n = 21) versus IMRT (n = 29). Postoperative complications were abstracted from medical records. Health care charges were obtained from institutional claims and adjusted for inflation (2021 dollars). Charge differences (Δ = $PBT - $IMRT) were compared by treatment using adjusted generalized linear models with the gamma distribution.

Results

Baseline PBT versus IMRT characteristics were not significantly different. In the observational cohort, during the neoadjuvant chemoradiation phase, health care charges were higher for PBT versus IMRT (Δ = +$71,959; 95% confidence interval [CI], $62,274-$82,138; P < .001). There was no difference in surgical charges (Δ = -$2234; 95% CI, -$6003 to $1695; P = .26). However, during postoperative hospitalization following esophagectomy, health care charges were lower for PBT versus IMRT (Δ = -$25,115; 95% CI, -$37,625 to -$9776; P = .003). In the comparison cohort, findings were analogous: Charges were higher for PBT versus IMRT during chemoradiation (Δ = +$61,818; 95% CI, $49,435-$75,069; P < .001), not different for surgery (Δ = -$4784; 95% CI, -$6439 to $3487; P = .25), and lower for PBT postoperatively (Δ = -$27,048; 95% CI, -$41,974 to -$5300; P = .02). Lower postoperative charges for PBT were especially seen among patients with any POCs in the contemporary comparison (Δ = -$176,448; 95% CI, -$209,782 to -$78,813; P = .02).

Conclusion

Higher up-front chemoradiation resource utilization for PBT in patients with EC was partially offset postoperatively, moderated by reduction in POC risks. Results extend existing clinical evidence of toxicity reduction with PBT.

Contemporary use and outcomes of radiation and chemotherapy for unresectable pancreatic cancer

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This study examines 5,624 patients with unresectable pancreatic cancer.

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Across “real-world” US practice, overall use of radiation treatment (RT) has declined.

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Among those receiving RT, stereotactic body radiation treatment (SBRT) increased.

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Contemporary risks of gastrointestinal complications after SBRT have decreased.

Background

We assessed radiation treatment (RT) use and complications for unresectable pancreatic cancer in the US, comparing conventionally fractionated (CFRT) and stereotactic body radiation treatment (SBRT) to inform real-world expected outcomes and practice.

Material and Methods

We analyzed 5,624 patients with non-metastatic, unresectable pancreatic cancer (2,522 older patients age > 65, diagnosed 2006–2013 in Medicare linked data; and 3,102 younger patients age < 65, diagnosed 2006–2016 in MarketScan data), comparing CFRT vs. SBRT vs. chemotherapy alone. Cochran-Armitage tested temporal trends. Fisher’s Exact Test and proportional hazards models compared gastrointestinal (GI) complications. Healthcare payments (Consumer Price Index adjusted to 2015) through 12 months were compared using generalized linear regression models with log link and gamma distribution.

Results

RT use declined from 55% to 45% of older patients (2006–2013) and 52% to 47% of younger patients (2006–2016) (Ptrend < 0.001 both). Among RT patients, SBRT use increased to 10% of older patients and 12% of younger patients in the most recent years (Ptrend = 0.04 and < 0.001 respectively). Addition of RT was associated with more frequent GI bleeds, strictures, and fistulas (Δ= +3% to 9% excess events, all P ≤ 0.05). Temporal patterns suggested decreasing complications over time (Ptrend = 0.05 and 0.05 for older and younger patients). Among younger patients, there was no difference in GI complications for SBRT vs. CFRT (P > 0.05, all comparisons). Among older patients, increased complications were seen for SBRT in 1–4 fractions vs. CFRT (P < 0.05), but not SBRT in 5 fractions (P = 0.72). Healthcare payments were greatest for SBRT when compared with CFRT or chemotherapy under US Medicare (P < 0.001) and employer-based insurance (P < 0.001).

Conclusion

Real-world treatment has shifted toward more selectivity for RT in unresectable pancreatic cancer. However, SBRT uptake and improving trends in complications profiles represent opportunities to optimize current use and benefit. Findings are applicable to inform future comparative and cost effectiveness models of RT for this disease.

Ablative liver radiotherapy for unresected intrahepatic cholangiocarcinoma: Patterns of care and survival in the United States

BACKGROUND

Single-institution studies have shown the oncologic benefit of ablative liver radiotherapy (A-RT) for patients with unresectable intrahepatic cholangiocarcinoma (ICC). However, adoption of A-RT across the United States and its associated outcomes are unknown.

METHODS

We queried the National Cancer Data Base for nonsurgically managed patients with ICC diagnosed between 2004 and 2018. Patients were labeled A-RT for receipt of biologically effective doses (BED10 ) ≥ 80.5 Gy and conventional RT (Conv-RT) for lower doses. Associations with A-RT use and overall survival were identified using logistic and Cox regressions, respectively.

RESULTS

Of 27,571 patients, the most common treatments were chemotherapy without liver RT (45%), no chemotherapy or liver RT (42%), and liver RT ± chemotherapy (13%). Use of liver RT remained constant over time. Of 1112 patients receiving liver RT with known doses, RT was 73% Conv-RT (median BED10 , 53 Gy; median, 20 fractions) and 27% A-RT (median BED10 , 100 Gy; median, 5 fractions). Use of A-RT increased from 5% in 2004 to 48% in 2018 (Ptrend < .001). With a median follow-up of 52.3 months, median survival estimates for Conv-RT and A-RT were 12.8 and 23.7 months (P < .001), respectively. On multivariable analysis, stage III and IV disease correlated with a higher risk of death, whereas chemotherapy and A-RT correlated with a lower risk.

CONCLUSIONS

Although A-RT has been increasingly used, use of liver RT as a whole in the United States remained constant despite growing evidence supporting its use, suggesting continued unmet need. A-RT is associated with longer survival versus Conv-RT.

LAY SUMMARY

Bile duct cancer is a rare, deadly disease that often presents at advanced stages. Single-institution retrospective studies have demonstrated that use of high-dose radiotherapy may be associated with longer survival, but larger studies have not been conducted. We used a large, national cancer registry of patients diagnosed between 2004 and 2018 to show that liver radiotherapy use remains low in the United States, despite growing evidence that patients who receive it live longer. Furthermore, we showed that patients who received high-dose radiotherapy lived longer than those who received lower doses. Greater awareness of the benefits of liver radiotherapy is needed to improve patient outcomes.

National Effort to Re-Establish Heavy Ion Cancer Therapy in the United States

In this review, we attempt to make a case for the establishment of a limited number of heavy ion cancer research and treatment facilities in the United States. Based on the basic physics and biology research, conducted largely in Japan and Germany, and early phase clinical trials involving a relatively small number of patients, we believe that heavy ions have a considerably greater potential to enhance the therapeutic ratio for many cancer types compared to conventional X-ray and proton radiotherapy. Moreover, with ongoing technological developments and with research in physical, biological, immunological, and clinical aspects, it is quite plausible that cost effectiveness of radiotherapy with heavier ions can be substantially improved.

Preservation of liver function with local radiation therapy in patients with metastatic intrahepatic cholangiocarcinoma with extrahepatic disease

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Background: Tumor related liver failure (TRLF) is the most common cause of death in patients with metastatic intrahepatic cholangiocarcinoma (mICC) accounting for up to 72% deaths in patients treated with systemic therapy alone. We present our institutional experience of treating mICC patients with local liver-directed radiation therapy (RT). Methods: ICC patients with extrahepatic metastatic disease who received radiation therapy at our center with a biologically equivalent dose (BED) of at least 50 Gy from January 1, 2011 to March 31, 2021 were included in our study. Patient, tumor and treatment characteristics as well as the survival outcomes were recorded. TRLF was considered the cause of death if the patient died due to liver failure; and freedom from TRLF (FFTRLF) at 1 year and 2 years after RT was calculated. Results: Sixty-seven patients were included in the study. The median age was 63 years (range 29-83 years) and median RT dose was 60 Gy (range, 40-100 Gy). 73.1% patients received a BED > 80.5 Gy. All except 1 patient were treated with upfront induction chemotherapy, followed by RT to the primary lesion in liver with (71.6%) or without (28.4%) concurrent chemotherapy. The most common induction chemotherapy regimen used was gemcitabine and cisplatin (65.7%) followed by gemcitabine, cisplatin and paclitaxel (22.4%), while the most common concurrent systemic therapy was capecitabine. Out of 43 patients with satellitosis, 29 were treated with RT to the dominant liver lesion while 14 received RT to the primary as well as one or more satellites. Overall, 15 patients (22.4%) had local progression of the radiated lesion, 42 patients (62.7%) progressed elsewhere in liver, and 52 patients (77.6%) had a distant progression. TRLF was the cause of death in 28.4% of patients. Median OS from diagnosis was 25 months while median OS after RT was 11.9 months. The 1- and 2-year rates of FFTRLF were 73.1% and 58.2% respectively, which were significantly higher than 1- and 2-year OS after RT (47.1% and 24.7% respectively, p < 0.005). Univariate analysis did not identify significant association of FFTRLF or OS with age, sex, performance status, size of liver lesions, T or N stage, satellitosis, vascular thrombosis, TRLF, timing of metastasis, site of metastasis, RT technique and dose and chemotherapy. Conclusions: Liver directed radiation therapy in patients with mICC with extrahepatic disease appears to have favorable rates of TRLF and survival times, compared to historical data. Future prospective studies are warranted to define the survival benefit in these patients attributable to radiation therapy.

Patient, physician, and policy factors underlying variation in use of telemedicine for radiation oncology cancer care

BACKGROUND

Oncology telemedicine was implemented rapidly after COVID-19. We examined multilevel correlates and outcomes of telemedicine use for patients undergoing radiotherapy (RT) for cancer.

METHODS

Upon implementation of a telemedicine platform at a comprehensive cancer center, we analyzed 468 consecutive patient RT courses from March 16, 2020 to June 1, 2020. Patients were categorized as using telemedicine during ≥1 weekly oncologist visits versus in-person oncologist management only. Temporal trends were evaluated with Cochran-Armitage tests; chi-squared test and multilevel multivariable logistic models identified correlates of use and outcomes.

RESULTS

Overall, 33% used telemedicine versus 67% in-person only oncologist management. Temporal trends (ptrend  < 0.001) correlated with policy changes: uptake was rapid after local social-distancing restrictions, reaching peak use (35% of visits) within 4 weeks of implementation. Use declined to 15% after national "Opening Up America Again" guidelines. In the multilevel model, patients more likely to use telemedicine were White non-Hispanic versus Black or Hispanic (odds ratio [OR] = 2.20, 95% confidence interval [CI] 1.03-4.72; p = 0.04) or receiving ≥6 fractions of RT versus 1-5 fractions (OR = 4.49, 95% CI 2.29-8.80; p < 0.001). Model intraclass correlation coefficient demonstrated 43% utilization variation was physician-level driven. Treatment toxicities and 30-day emergency visits or unplanned hospitalizations did not differ for patients using versus not using telemedicine (p > 0.05, all comparisons).

CONCLUSION

Though toxicities were similar with telemedicine oncology management, there remained lower uptake among non-White patients. Continuing strategies for oncology telemedicine implementation should address multilevel patient, physician, and policy factors to optimize telemedicine's potential to surmount-and not exacerbate-barriers to quality cancer care.

Gastrointestinal malignancies and supportive care trials: a snapshot of the last two decades

BACKGROUND

Patients with gastrointestinal (GI) cancers experience a high symptom burden due to the effects of both cancer and treatment. As such, trials assessing symptom burden and supportive interventions are crucial. Here, we characterise the landscape of phase III GI cancer clinical trials and explore study outcomes centred on the patient's quality of life (QoL).

METHODS

We searched ClinicalTrials.gov for phase III randomised controlled trials (RCTs) registered between 2000 and 2017 that are assessing a therapeutic intervention in adult patients with cancer and grouped trials by GI disease sites.

RESULTS

Overall, we identified 76 phase III trials specific to GI cancers that enrolled a total of 53 725 patients. When analysing the primary outcomes measured, the vast majority of studies (n=71, 86%) measured disease-related endpoints such as progression-free survival or overall survival. All trials had a secondary endpoint that measured adverse events, but only 30 trials (39%) included QoL measures as secondary endpoints. Of the 30 trials that included QoL secondary endpoints, only 16 (53%) reported these results. Only five trials (7%) assessed interventions aimed at supportive measures impacting disease-related or treatment-related toxicity. None of the supportive trials included QoL as a primary endpoint and only two of these trials (40%) included QoL as a secondary endpoint.

CONCLUSIONS

Most GI cancer trials failed to incorporate patient-centred outcomes or QoL measures when studying new interventions. These findings call for greater integration of patient-reported metrics, which may lead to better care and outcomes for patients with GI malignancies.

Benchmarking Outcomes for Definitive Treatment of Young-Onset, Locally Advanced Rectal Cancer

PURPOSE

There has been an increase in the incidence of rectal cancer diagnosed in young adults (age < 50 years). We evaluated outcomes among young adults treated with pre-operative long course chemoradiation (CRT) and total mesorectal excision (TME).

METHODS

The medical records of 219 patients, age 18-49, with non-metastatic, cT3-4, or cN1-2 rectal adenocarcinoma treated from 2000 to 2017 were reviewed for demographic and treatment characteristics, as well as pathologic and oncologic outcomes. The Kaplan-Meier test, log-rank test, and Cox regression analysis were used to evaluate survival outcomes.

RESULTS

The median age at diagnosis was 44 years. CRT followed by TME and post-operative chemotherapy was the most frequent treatment sequence (n = 196), with FOLFOX (n = 115) as the predominant adjuvant chemotherapy. There was no difference in sex, stage, MSS/pMMR, or pCR by age (< 45 years [n = 111] vs. ≥ 45 years [n = 108]). The 5-year rates of DFS were 77.2% for all patients, 69.8% for age < 45 years and 84.7% for age ≥ 45 years (P = .01). The 5-year rates of OS were 89.6% for all patients, 85.1% for patients with age < 45 years and 94.3% for patients with age ≥ 45 years (P = .03). Age ≥ 45 years was associated with a lower risk of disease recurrence or death on multivariable Cox regression analysis (HR = 0.55, 95% CI 0.31-0.97, P = .04).

CONCLUSION

Among young adults, patients with age < 45 years had lower rates of DFS and OS, compared to those with age ≥ 45 years. These outcomes could serve as a benchmark by which to evaluate newer treatment approaches.

Stress-induced tyrosine phosphorylation of RtcB modulates IRE1 activity and signaling outputs

ER stress is mediated by three sensors and the most evolutionary conserved IRE1α signals through its cytosolic kinase and endoribonuclease (RNase) activities. IRE1α RNase activity can either catalyze the initial step of XBP1 mRNA unconventional splicing or degrade a number of RNAs through regulated IRE1-dependent decay. Until now, the biochemical and biological outputs of IRE1α RNase activity have been well documented; however, the precise mechanisms controlling whether IRE1α signaling is adaptive or pro-death (terminal) remain unclear. We investigated those mechanisms and hypothesized that XBP1 mRNA splicing and regulated IRE1-dependent decay activity could be co-regulated by the IRE1α RNase regulatory network. We identified that RtcB, the tRNA ligase responsible for XBP1 mRNA splicing, is tyrosine-phosphorylated by c-Abl and dephosphorylated by PTP1B. Moreover, we show that the phosphorylation of RtcB at Y306 perturbs RtcB interaction with IRE1α, thereby attenuating XBP1 mRNA splicing. Our results demonstrate that the IRE1α RNase regulatory network is dynamically fine-tuned by tyrosine kinases and phosphatases upon various stresses and that the extent of RtcB tyrosine phosphorylation determines cell adaptive or death outputs.

Expansion of Candidate HPV-Specific T Cells in the Tumor Microenvironment during Chemoradiotherapy Is Prognostic in HPV16+ Cancers

Human papillomavirus (HPV) infection causes 600,000 new cancers worldwide each year. HPV-related cancers express the oncogenic proteins E6 and E7, which could serve as tumor-specific antigens. It is not known whether immunity to E6 and E7 evolves during chemoradiotherapy or affects survival. Using T cells from 2 HPV16⁺ patients, we conducted functional T-cell assays to identify candidate HPV-specific T cells and common T-cell receptor motifs, which we then analyzed across 86 patients with HPV-related cancers. The HPV-specific clones and E7-related T-cell receptor motifs expanded in the tumor microenvironment over the course of treatment, whereas non-HPV-specific T cells did not. In HPV16⁺ patients, improved recurrence-free survival was associated with HPV-responsive T-cell expansion during chemoradiotherapy.

Definitive Intensity-Modulated Chemoradiation for Anal Squamous Cell Carcinoma: Outcomes and Toxicity of 428 Patients Treated at a Single Institution

Background

Although intensity-modulated radiation therapy (IMRT) is considered the standard of care for the treatment of squamous cell carcinoma of the anus (SCCA), few large series have reported oncologic outcomes and toxicities. In this retrospective report, we aim to describe outcomes and toxicities after IMRT-based chemoradiation (CRT) for the treatment of SCCA, evaluate the impact of dose escalation (&gt;54 Gy), and compare concurrent fluoropyrimidine in combination with either mitomycin or with cisplatin as chemosensitizers.

Methods

Patients treated at The University of Texas MD Anderson Cancer Center between January 1, 2003 and December 31, 2018 with IMRT-based CRT were included. Median time to locoregional recurrence, time to colostomy, and overall survival were estimated using the Kaplan–Meier method.

Results

A total of 428 patients were included; median follow-up was 4.4 years. Three hundred and thirty-four patients (78.0%) were treated with concurrent cisplatin and fluoropyrimidine, and 160 (37.4%) with &gt;54 Gy. Two- and 5-year freedom from locoregional failure, freedom from colostomy failure, and overall survival were 86.5% and 81.2%, respectively, 90.0% and 88.3%, respectively, and 93.6% and 85.8%, respectively. Neither dose escalation nor mitomycin-based concurrent chemotherapy resulted in improved outcomes. Mitomycin-based concurrent chemotherapy was associated with in approximately 2.5 times increased grade 3 or greater acute toxicity. Radiation dose &gt;54 Gy was associated with approximately 2.6 times increased Grade 3 or greater chronic toxicity.

Conclusions

Our results suggest IMRT-based CRT with concurrent fluoropyrimidine and cisplatin is a safe and feasible option for patient with SCCA and may cause less acute toxicity. The role for radiation dose escalation is unclear and requires further study.

The radiotherapy quality assurance gap among phase III cancer clinical trials

PURPOSE

Quality assurance (QA) practices improve the quality level of oncology trials by ensuring that the protocol is followed and the results are valid and reproducible. This study investigated the utilization of QA among randomized controlled trials that involve radiotherapy (RT).

METHODS AND MATERIALS

We searched ClinicalTrials.gov in February 2020 for all phase III oncology randomized clinical trials (RCTs). These trials were screened for RT-specific RCTs that had published primary trial results. Information regarding QA in each trial was collected from the study publications and trial protocol if available. Two individuals independently performed trial screening and data collection. Pearson's Chi-square tests analyses were used to assess factors that were associated with QA inclusion in RT trials.

RESULTS

Forty-two RCTs with RT as the primary intervention or as a mandatory component of the protocol were analyzed; the earliest was started in 1994 and one trial was still active though not recruiting. Twenty-nine (69%) trials mandated RT quality assurance (RTQA) practices as part of the trial protocol, with 19 (45%) trials requiring institutional credentialing. Twenty-one (50%) trials published protocol deviation outcomes. Clinical trials involving advanced radiation techniques (IMRT, VMAT, SRS, SBRT) did not include more RTQA than trials without these advanced techniques (73% vs. 65%, p = 0.55). Trials that reported protocol deviation outcomes were associated with mandating RTQA in their protocols as compared to trials that did not report these outcomes (100% vs. 38%, p < 0.001).

CONCLUSIONS

There is a lack of RTQA utilization and transparency in RT clinical trials. It is imperative for RT trials to include increased QA for safe, consistent, and high-quality RT planning and delivery.

Benchmarking Outcomes after Ablative Radiotherapy for Molecularly Characterized Intrahepatic Cholangiocarcinoma

We have previously shown that ablative radiotherapy (A-RT) with a biologically effective dose (BED10) ≥ 80.5 Gy for patients with unresectable intrahepatic cholangiocarcinoma (ICC) is associated with longer survival. Despite recent large-scale sequencing efforts in ICC, outcomes following RT based on genetic alterations have not been described. We reviewed records of 156 consecutive patients treated with A-RT for unresectable ICC from 2008 to 2020. For 114 patients (73%), next-generation sequencing provided molecular profiles. The overall survival (OS), local control (LC), and distant metastasis-free survival (DMFS) were estimated using the Kaplan-Meier method. Univariate and multivariable Cox analyses were used to determine the associations with the outcomes. The median tumor size was 7.3 (range: 2.2-18.2) cm. The portal vein thrombus (PVT) was present in 10%. The RT median BED10 was 98 Gy (range: 81-144 Gy). The median (95% confidence interval) follow-up was 58 (42-104) months from diagnosis and 39 (33-74) months from RT. The median OS was 32 (29-35) months after diagnosis and 20 (16-24) months after RT. The one-year OS, LC, and intrahepatic DMFS were 73% (65-80%), 81% (73-87%), and 34% (26-42%). The most common mutations were in IDH1 (25%), TP53 (22%), ARID1A (19%), and FGFR2 (13%). Upon multivariable analysis, the factors associated with death included worse performance status, larger tumor, metastatic disease, higher CA 19-9, PVT, satellitosis, and IDH1 and PIK3CA mutations. TP53 mutation was associated with local failure. Further investigation into the prognostic value of individual mutations and combinations thereof is warranted.

Design and validation of a synchrotron proton beam line for FLASH radiotherapy preclinical research experiments

PURPOSE

The main purpose of this work was to generate and validate the dosimetric accuracy of proton beams of dimensions that are appropriate for in vivo small animal and in vitro ultrahigh dose rate (FLASH) radiotherapy experiments using a synchrotron-based treatment delivery system. This study was performed to enable future investigations of the relevance of a spread-out Bragg peak (SOBP) under FLASH conditions.

METHODS

The spill characteristics of the small field fixed horizontal beam line were modified to deliver accelerated protons in times as short as 2 ms and to control the dose delivered. A Gaussian-like transverse beam profile was transformed into a square uniform one at FLASH dose rates, while avoiding low-dose regions, a crucial requirement to protect normal tissue during FLASH irradiation. Novel beam-shaping devices were designed using Monte Carlo techniques to produce up to about 6 cm³ of uniform dose in SOBPs while maximizing the dose rate. These included a scattering foil, a conical flattening filter to maximize the flux of protons into the region of interest, energy filters, range compensators, and collimators. The shapes, sizes, and positions of the components were varied to provide the required field sizes and SOBPs.

RESULTS

The designed and fabricated devices were used to produce 10-, 15-, and 20-mm diameter, circular field sizes and 10-, 15-, and 20-mm SOBP modulation widths at uniform physical dose rates of up to 375 Gy/s at the center of the SOBP and a minimum dose rate of about 255 Gy/s at the entrance, respectively, in cylindrical volumes. The flatness of lateral dose profiles at the center could be adjusted to within ±1.5% at the center of the SOBP. Assessment of systematic uncertainties, such as impact of misalignments and positioning uncertainties, was performed using simulations, and the results were used to provide appropriate adjustments to ensure high-accuracy FLASH beam delivery for both in vitro and in vivo preclinical experiments.

CONCLUSIONS

It is feasible to use synchrotron-generated proton beams of sufficient dimensions for FLASH radiobiology experiments. We expect to use the system we developed to acquire in vitro and in vivo small animal FLASH radiobiology data as a function of dose, dose rate, oxygen content, and linear energy transfer to help us understand the underlying mechanisms of the FLASH phenomenon.

Prognostic impact of lymphopenia and neutrophil-lymphocyte ratio for patients with anal squamous cell carcinoma

Background

Outcomes after definitive chemoradiation for squamous cell carcinoma are generally favorable. However, biomarkers to further yield prognostic information are desired. Treatment-related lymphopenia as well as an elevated baseline neutrophil-lymphocyte ratio have been associated with worse survival in several cancer types. We evaluated absolute lymphocyte count and neutrophil-lymphocyte ratio at baseline and at treatment-related nadir in patients with anal cancer for associations with oncologic endpoints.

Methods

We conducted a retrospective analysis of 428 consecutive patients with non-metastatic anal cancer treated with definitive, intensity-modulated radiation therapy-based chemoradiation. We analyzed absolute neutrophil and lymphocyte counts at several timepoints: pretreatment, weekly during treatment, and in the six weeks following treatment completion. Neutrophil-lymphocyte ratio was calculated at baseline and treatment-related nadir. We estimated oncologic endpoints using life tables and compared them using the log-rank test. We conducted univariate and multivariable time-to-event analyses using Cox proportional hazards.

Results

Median absolute lymphocyte count at baseline and nadir were 1.80 [interquartile range (IQR), 1.45-2.32] k/µL and 0.26 (IQR, 0.18-0.36) k/µL, respectively, and 31% developed treatment-related grade 4 lymphopenia. Median neutrophil-lymphocyte ratio at baseline and nadir were 2.34 (IQR, 1.68-3.30) and 8.80 (IQR, 5.86-12.68), respectively. Estimates of overall survival, local failure-free survival, distant metastasis-free survival (DMFS), and freedom from colostomy at 5 years were 87%, 86%, 82%, and 88%, respectively. Baseline and nadir absolute lymphocyte count were not associated with selected outcomes on univariate analysis. On multivariable analysis, factors independently associated with death included T3-T4 disease, HIV-positive status, treatment break, and baseline neutrophil-lymphocyte ratio >3. Baseline neutrophil-lymphocyte ratio showed a trend toward association with distant progression or death (P=0.07). The 5-year overall survival estimates for patients with baseline neutrophil-lymphocyte ratios ≤3 and >3 were 92.3% and 80.6%, respectively.

Conclusions

Lymphopenia during and after chemoradiation for anal cancer is common but does not appear to be associated with worse survival, recurrence, or metastases. However, elevated baseline neutrophil-lymphocyte ratio was independently associated with overall survival, local recurrence-free survival, and DMFS. Further studies are needed to determine the clinical utility of baseline neutrophil-lymphocyte ratio to guide treatment and follow-up.