Total Neoadjuvant Therapy in Rectal Cancer: Multi-center Comparison of Induction Chemotherapy and Long-Course Chemoradiation Versus Short-Course Radiation and Consolidative Chemotherapy

BACKGROUND

Total neoadjuvant therapy for locally advanced rectal cancer may include induction chemotherapy and chemoradiation or short-course radiotherapy and consolidative chemotherapy.

METHODS

Patients with clinical stage 2 or 3 rectal cancer who received induction chemotherapy followed by long-course chemoradiation at the University of Colorado (2016-2020) or short-course radiotherapy followed by consolidative chemotherapy at Washington University (2017-2020) were assessed.

RESULTS

Eighty-four patients received induction chemotherapy and chemoradiation and 83 received short-course radiotherapy and consolidative chemotherapy. Among patients with complete re-staging evaluation, clinical complete response rates were similar, 49% (18/37) and 53% (44/83), respectively (p = 0.659). In the induction chemotherapy and chemoradiation group, 80% (n = 67) underwent surgery and 28% (n = 19) achieved a pathologic complete response. In the short-course radiotherapy and consolidative chemotherapy group, 44 (53%) patients underwent surgery and 11% (n = 5) had a pathologic complete response. Overall, a complete response was observed in 43% (n = 36) of patients who received induction chemotherapy and chemoradiation compared to 53% (n = 44) who received short-course radiotherapy and consolidative chemotherapy (p = 0.189). Perioperative outcomes were similar in patients who received induction chemotherapy and chemoradiation compared to short-course radiotherapy and consolidative chemotherapy: intraoperative complications (2% vs 7%), complete mesorectal specimen (85% vs 84%), anastomotic leak (9% vs 7%), organ/space infection (9% vs 5%), readmission (19% vs 21%), and reoperation (8% vs 9%), respectively (all p > 0.05).

CONCLUSIONS

In patients with clinical stage 2 or 3 rectal cancer, total neoadjuvant therapy with either induction chemotherapy and chemoradiation or short-course radiotherapy followed by consolidative chemotherapy were associated with similar perioperative morbidity and complete response rates.

MR-Guided Radiation Therapy With Concurrent Gemcitabine/Nab-Paclitaxel Chemotherapy in Inoperable Pancreatic Cancer: A TITE-CRM Phase I Trial

PURPOSE

Ablative radiation therapy for borderline resectable or locally advanced pancreatic ductal adenocarcinoma (BR/LA-PDAC) may limit concurrent chemotherapy dosing and usually is only safely deliverable to tumors distant from gastrointestinal organs. Magnetic resonance guided radiation therapy may safely permit radiation and chemotherapy dose escalation.

METHODS AND MATERIALS

We conducted a single-arm phase I study to determine the maximum tolerated dose of ablative hypofractionated radiation with full-dose gemcitabine/nab-paclitaxel in patients with BR/LA-PDAC. Patients were treated with gemcitabine/nab-paclitaxel (1000/125 mg/m2) x 1c then concurrent gemcitabine/nab-paclitaxel and radiation. Gemcitabine/nab-paclitaxel and radiation doses were escalated per time-to-event continual reassessment method from 40 to 45 Gy 25 fxs with chemotherapy (600-800/75 mg/m2) to 60 to 67.5 Gy/15 fractions and concurrent gemcitabine/nab-paclitaxel (1000/100 mg/m2). The primary endpoint was maximum tolerated dose of radiation as defined by 60-day dose limiting toxicity (DLT). DLT was treatment-related G5, G4 hematologic, or G3 gastrointestinal requiring hospitalization >3 days. Secondary endpoints included resection rates, local progression free survival (LPFS), distant metastasis free survival (DMFS), and overall survival (OS).

RESULTS

Thirty patients enrolled (March 2015-February 2019), with 26 evaluable patients (2 progressed before radiation, 1 was determined ineligible for radiation during planning, 1 withdrew consent). One DLT was observed. The DLT rate was 14.1% (3.3%-24.9%) with a maximum tolerated dose of gemcitabine/nab-paclitaxel (1000/100 mg/m2) and 67.5 Gy/15 fractions. At a median follow-up of 40.6 months for living patients the median OS was 14.5 months (95% confidence interval [CI], 10.9-28.2 months). The median OS for patients with Eastern Collaborative Oncology Group 0 and carbohydrate antigen 19-9 <90 were 34.1 (95% CI, 13.6-54.1) and 43.0 (95% CI, 8.0-not reached) months, respectively. Two-year LPFS and DMFS were 85% (95% CI, 63%-94%) and 57% (95% CI, 34%-73%), respectively.

CONCLUSIONS

Full-dose gemcitabine/nab-paclitaxel with ablative magnetic resonance guided radiation therapy dosing is safe in patients with BR/LA-PDAC, with promising LPFS and DMFS.

Magnetic resonance biomarkers in radiation oncology: The report of AAPM Task Group 294

A magnetic resonance (MR) biologic marker (biomarker) is a measurable quantitative characteristic that is an indicator of normal biological and pathogenetic processes or a response to therapeutic intervention derived from the MR imaging process. There is significant potential for MR biomarkers to facilitate personalized approaches to cancer care through more precise disease targeting by quantifying normal versus pathologic tissue function as well as toxicity to both radiation and chemotherapy. Both of which have the potential to increase the therapeutic ratio and provide earlier, more accurate monitoring of treatment response. The ongoing integration of MR into routine clinical radiation therapy (RT) planning and the development of MR guided radiation therapy systems is providing new opportunities for MR biomarkers to personalize and improve clinical outcomes. Their appropriate use, however, must be based on knowledge of the physical origin of the biomarker signal, the relationship to the underlying biological processes, and their strengths and limitations. The purpose of this report is to provide an educational resource describing MR biomarkers, the techniques used to quantify them, their strengths and weakness within the context of their application to radiation oncology so as to ensure their appropriate use and application within this field.

Nonoperative Rectal Cancer Management With Short-Course Radiation Followed by Chemotherapy: A Nonrandomized Control Trial

PURPOSE

Short-course radiation therapy (SCRT) and nonoperative management are emerging paradigms for rectal cancer treatment. This clinical trial is the first to evaluate SCRT followed by chemotherapy as a nonoperative treatment modality.

METHODS

Patients with nonmetastatic rectal adenocarcinoma were treated on the single-arm, Nonoperative Radiation Management of Adenocarcinoma of the Lower Rectum study of SCRT followed by chemotherapy. Patients received 25 Gy in 5 fractions to the pelvis followed by FOLFOX ×8 or CAPOX ×5 cycles. Patients with clinical complete response (cCR) underwent nonoperative surveillance. The primary end point was cCR at 1 year. Secondary end points included safety profile and anorectal function.

RESULTS

From June 2016 to March 2019, 19 patients were treated (21% stage I, 32% stage II, and 47% stage III disease). At a median follow-up of 27.7 months for living patients, the 1-year cCR rate was 68%. Eighteen of 19 patients are alive without evidence of disease. Patients with cCR versus without had improved 2-year disease-free survival (93% vs 67%; P = .006), distant metastasis-free survival (100% vs 67%; P = .03), and overall survival (100% vs 67%; P = .03). Involved versus uninvolved circumferential resection margin on magnetic resonance imaging was associated with less initial cCR (40% vs 93%; P = .04). Anorectal function by Functional Assessment of Cancer Therapy-Colorectal cancer score at 1 year was not different than baseline. There were no severe late effects.

CONCLUSIONS

Treatment with SCRT and chemotherapy resulted in high cCR rate, intact anorectal function, and no severe late effects. NCT02641691.

Adaptive Radiation Therapy (ART) Strategies and Technical Considerations: A State of the ART Review From NRG Oncology

The integration of adaptive radiation therapy (ART), or modifying the treatment plan during the treatment course, is becoming more widely available in clinical practice. ART offers strong potential for minimizing treatment-related toxicity while escalating or de-escalating target doses based on the dose to organs at risk. Yet, ART workflows add complexity into the radiation therapy planning and delivery process that may introduce additional uncertainties. This work sought to review presently available ART workflows and technological considerations such as image quality, deformable image registration, and dose accumulation. Quality assurance considerations for ART components and minimum recommendations are described. Personnel and workflow efficiency recommendations are provided, as is a summary of currently available clinical evidence supporting the implementation of ART. Finally, to guide future clinical trial protocols, an example ART physician directive and a physics template following standard NRG Oncology protocol is provided.

Using adaptive magnetic resonance image-guided radiation therapy for treatment of inoperable pancreatic cancer

Background

Adaptive magnetic resonance imaging‐guided radiation therapy (MRgRT) can escalate dose to tumors while minimizing dose to normal tissue. We evaluated outcomes of inoperable pancreatic cancer patients treated using MRgRT with and without dose escalation.

Methods

We reviewed 44 patients with inoperable pancreatic cancer treated with MRgRT. Treatments included conventional fractionation, hypofractionation, and stereotactic body radiation therapy. Patients were stratified into high‐dose (biologically effective dose [BED₁₀] >70) and standard‐dose groups (BED₁₀ ≤70). Overall survival (OS), freedom from local failure (FFLF) and freedom from distant failure (FFDF) were evaluated using Kaplan‐Meier method. Cox regression was performed to identify predictors of OS. Acute gastrointestinal (GI) toxicity was assessed for 6 weeks after completion of RT.

Results

Median follow‐up was 17 months. High‐dose patients (n = 24, 55%) had statistically significant improvement in 2‐year OS (49% vs 30%, P = 0.03) and trended towards significance for 2‐year FFLF (77% vs 57%, P = 0.15) compared to standard‐dose patients (n = 20, 45%). FFDF at 18 months in high‐dose vs standard‐dose groups was 24% vs 48%, respectively (P = 0.92). High‐dose radiation (HR: 0.44; 95% confidence interval [CI]: 0.21‐0.94; P = 0.03) and duration of induction chemotherapy (HR: 0.84; 95% CI: 0.72‐0.98; P = 0.03) were significantly correlated with OS on univariate analysis but neither factor was independently predictive on multivariate analysis. Grade 3+ GI toxicity occurred in three patients in the standard‐dose group and did not occur in the high‐dose group.

Conclusions

Patients treated with dose‐escalated MRgRT demonstrated improved OS. Prospective evaluation of high‐dose RT regimens with standardized treatment parameters in inoperable pancreatic cancer patients is warranted.

Anal Cancer in the Era of Dose Painted Intensity Modulated Radiation Therapy: Implications for Regional Nodal Therapy

Since the initial development of 5-fluorouracil and mitomycin as a standard of care platform for definitive anal cancer chemoradiotherapy, multiple studies have evaluated the optimal chemotherapy regimen, and radiotherapy technique. Refinements in treatment technique have taken place during an era of improved diagnostic imaging, including incorporation of FDG-PET, with implications for a possible stage migration effect. This has introduced an opportunity to develop stage-specific recommendations for primary tumor, involved nodal, and elective nodal irradiation dose. Elective nodal irradiation remains standard given the low rates of elective nodal failure with current practice, although may be subject to evolving controversy for patients with early stage disease. In this review, development of the current standard of care for anal cancer chemoradiotherapy is reviewed in the context of modern staging and dose-painted radiotherapy treatment techniques.

Magnetic Resonance Image-Guided Radiotherapy (MRIgRT): A 4.5-Year Clinical Experience

AIMS

Magnetic resonance image-guided radiotherapy (MRIgRT) has been clinically implemented since 2014. This technology offers improved soft-tissue visualisation, daily imaging, and intra-fraction real-time imaging without added radiation exposure, and the opportunity for adaptive radiotherapy (ART) to adjust for anatomical changes. Here we share the longest single-institution experience with MRIgRT, focusing on trends and changes in use over the past 4.5 years.

MATERIALS AND METHODS

We analysed clinical information, including patient demographics, treatment dates, disease sites, dose/fractionation, and clinical trial enrolment for all patients treated at our institution using MRIgRT on a commercially available, integrated 0.35 T MRI, tri-cobalt-60 device from 2014 to 2018. For each patient, factors including disease site, clinical rationale for MRIgRT use, use of ART, and proportion of fractions adapted were summated and compared between individual years of use (2014-2018) to identify shifts in institutional practice patterns.

RESULTS

Six hundred and forty-two patients were treated with 666 unique treatment courses using MRIgRT at our institution between 2014 and 2018. Breast cancer was the most common disease, with use of cine MRI gating being a particularly important indication, followed by abdominal sites, where the need for cine gating and use of ART drove MRIgRT use. One hundred and ninety patients were treated using ART in 1550 fractions, 67.6% (1050) of which were adapted. ART was primarily used in cancers of the abdomen. Over time, breast and gastrointestinal cancers became increasingly dominant for MRIgRT use, hypofractionated treatment courses became more popular, and gastrointestinal cancers became the principal focus of ART.

DISCUSSION

MRIgRT is widely applicable within the field of radiation oncology and new clinical uses continue to emerge. At our institution to date, applications such as ART for gastrointestinal cancers and accelerated partial breast irradiation (APBI) for breast cancer have become dominant indications, although this is likely to continue to evolve.

Stereotactic MR-Guided Online Adaptive Radiation Therapy (SMART) for Ultracentral Thorax Malignancies: Results of a Phase 1 Trial

Purpose

Stereotactic body radiation therapy (SBRT) is an effective treatment for oligometastatic or unresectable primary malignancies, although target proximity to organs at risk (OARs) within the ultracentral thorax (UCT) limits safe delivery of an ablative dose. Stereotactic magnetic resonance (MR)–guided online adaptive radiation therapy (SMART) may improve the therapeutic ratio using reoptimization to account for daily variation in target and OAR anatomy. This study assessed the feasibility of UCT SMART and characterized dosimetric and clinical outcomes in patients treated for UCT lesions on a prospective phase 1 trial.

Methods and Materials

Five patients with oligometastatic (n = 4) or unresectable primary (n = 1) UCT malignancies underwent SMART. Initial plans prescribed 50 Gy in 5 fractions with goal 95% planning target volume (PTV) coverage by 95% of prescription, subject to strict OAR constraints. Daily real-time online adaptive plans were created as needed to preserve hard OAR constraints, escalate PTV dose, or both, based on daily setup MR image set anatomy. Treatment times, patient outcomes, and dosimetric comparisons were prospectively recorded.

Results

All initial and daily adaptive plans met strict OAR constraints based on simulation and daily setup MR imaging anatomy, respectively. Four of the 5 patients received ≥1 adapted fraction. Ten of the 25 total delivered fractions were adapted. A total of 30% of plan adaptations were performed to improve PTV coverage; 70% were for reversal of ≥1 OAR violation. Local control by Response Evaluation Criteria in Solid Tumors was 100% at 3 and 6 months. No grade ≥3 acute (within 6 months of radiation completion) treatment-related toxicities were identified.

Conclusions

SMART may allow PTV coverage improvement and/or OAR sparing compared with nonadaptive SBRT and may widen the therapeutic index of UCT SBRT. In this small prospective cohort, we found that SMART was clinically deliverable to 100% of patients, although treatment delivery times surpassed our predefined, timing-based feasibility endpoint. This technique is well tolerated, offering excellent local control with no identified acute grade ≥3 toxicity.

Predictors of Survival after Yttrium-90 Radioembolization for Colorectal Cancer Liver Metastases

PURPOSE

To identify clinical parameters that are prognostic for improved overall survival (OS) after yttrium-90 radioembolization (RE) in patients with liver metastases from colorectal cancer (CRC).

MATERIALS AND METHODS

A total of 131 patients who underwent RE for liver metastases from CRC, treated at 2 academic centers, were reviewed. Twenty-one baseline pretreatment clinical factors were analyzed in relation to OS by the Kaplan-Meier method along with log-rank tests and univariate and multivariate Cox regression analyses.

RESULTS

The median OS from first RE procedure was 10.7 months (95% confidence interval [CI], 9.4-12.7 months). Several pretreatment factors, including lower carcinoembryonic antigen (CEA; ≤20 ng/mL), lower aspartate transaminase (AST; ≤40 IU/L), neutrophil-lymphocyte ratio (NLR) <5, and absence of extrahepatic disease at baseline were associated with significantly improved OS after RE, compared with high CEA (>20 ng/mL), high AST (>40 IU/L), NLR ≥5, and extrahepatic metastases (P values of <.001, <.001, .0001, and .04, respectively). On multivariate analysis, higher CEA, higher AST, NLR ≥5, extrahepatic disease, and larger volume of liver metastases remained independently associated with risk of death (hazard ratios of 1.63, 2.06, 2.22, 1.48, and 1.02, respectively).

CONCLUSIONS

The prognosis of patients with metastases from CRC is impacted by a complex set of clinical parameters. This analysis of pretreatment factors identified lower AST, lower CEA, lower NLR, and lower tumor burden (intra- or extrahepatic) to be independently associated with higher survival after hepatic RE. Optimal selection of patients with CRC liver metastases may improve survival rates after administration of yttrium-90.

First clinical implementation of real-time, real anatomy tracking and radiation beam control

PURPOSE

We describe the acceptance testing, commissioning, periodic quality assurance, and workflow procedures developed for the first clinically implemented magnetic resonance imaging-guided radiation therapy (MR-IGRT) system for real-time tracking and beam control.

METHODS

The system utilizes real-time cine imaging capabilities at 4 frames per second for real-time tracking and beam control. Testing of the system was performed using an in-house developed motion platform and a commercially available motion phantom. Anatomical tracking is performed by first identifying a target (a region of interest that is either tissue to be treated or a critical structure) and generating a contour around it. A boundary contour is also created to identify tracking margins. The tracking algorithm deforms the anatomical contour (target or a normal organ) on every subsequent cine frame and compares it to the static boundary contour. If the anatomy of interest moves outside the boundary, the radiation delivery is halted until the tracked anatomy returns to treatment portal. The following were performed to validate and clinically implement the system: (a) spatial integrity evaluation; (b) tracking accuracy; (c) latency; (d) relative point dose and spatial dosimetry; (e) development of clinical workflow for gating; and (f) independent verification by an outside credentialing service.

RESULTS

The spatial integrity of the MR system was found to be within 2 mm over a 45-cm diameter field-of-view. The tracking accuracy for geometric targets was within 1.2 mm. The average system latency was measured to be within 394 ms. The dosimetric accuracy using ionization chambers was within 1.3% ± 1.7%, and the dosimetric spatial accuracy was within 2 mm. The phantom irradiation for the outside credentialing service had satisfactory results, as well.

CONCLUSIONS

The first clinical MR-IGRT system was validated for real-time tracking and gating capabilities and shown to be reliable and accurate. Patient workflow methods were developed for efficient treatment. Periodic quality assurance tests can be efficiently performed with commercially available equipment to ensure accurate system performance.

Improved Metastasis- and Disease-Free Survival With Preoperative Sequential Short-Course Radiation Therapy and FOLFOX Chemotherapy for Rectal Cancer Compared With Neoadjuvant Long-Course Chemoradiotherapy: Results of a Matched Pair Analysis

PURPOSE

To compare treatment and toxicity outcomes between a phase 2 institutional trial of near total neoadjuvant therapy (nTNT) for locally advanced rectal cancer and a similar historical control cohort treated at Washington University in St. Louis with the current US standard of care, defined as neoadjuvant chemoradiotherapy (NCRT), total mesorectal excision (TME), and adjuvant FOLFOX chemotherapy; to expand the comparison to an additional institution, patients treated with similar NCRT at Stanford University were included.

METHODS AND MATERIALS

Sixty-nine patients with cT3-4N0-2M0 rectal adenocarcinoma enrolled on the Washington University in St. Louis phase 2 study of nTNT were included for analysis. Patients treated at the same institution with conventional NCRT and adjuvant FOLFOX were matched for exact cTNM stage. Forty-one patients treated with NCRT at Stanford University were included in a second analysis. Kaplan-Meier analysis with log-rank test was used to compare local control, distant metastasis-free survival, disease-free survival, and overall survival.

RESULTS

Median follow-up was 49 and 54 months for nTNT and NCRT, respectively. Pathologic complete response and T-downstaging rates were 28% versus 16% (P=.21) and 75% versus 41% (P<.001) in the nTNT and NCRT cohorts, respectively. Three-year disease-free survival (85% vs 68%, P=.032) was significantly better in the nTNT group. Actuarial 3-year local control (92% vs 96%, P=.36) and overall survival (96% vs 88%, P=.67) were similar. The Stanford cohort had significantly lower clinical stage. After controlling for clinical stage, age, tumor location, institution, and number of chemotherapy cycles, nTNT treatment remained significantly associated with lower risk of recurrence (P=.006).

CONCLUSIONS

Patients treated with nTNT had higher T-downstaging and superior distant metastasis-free survival and disease-free survival compared with conventional NCRT when matched for tumor location and exact cTNM stage. Near total neoadjuvant therapy remained a significant multivariate predictor for improved outcome when including patients treated with NCRT at another institution.

Two-and-a-half-year clinical experience with the world's first magnetic resonance image guided radiation therapy system

Purpose

Magnetic resonance image guided radiation therapy (MR-IGRT) has been used at our institution since 2014. We report on more than 2 years of clinical experience in treating patients with the world's first MR-IGRT system.

Methods and materials

A clinical service was opened for MR-IGRT in January 2014 with an MR-IGRT system consisting of a split 0.35T magnetic resonance scanner that straddles a ring gantry with 3 multileaf collimator-equipped ⁶⁰Co heads. The service was expanded to include online adaptive radiation therapy (ART) MR-IGRT and cine gating after 6 and 9 months, respectively. Patients selected for MR-IGRT were enrolled in a prospective registry between January 2014 and June 2016. Patients were treated with a variety of radiation therapy techniques including intensity modulated radiation therapy and stereotactic body radiation therapy (SBRT). When applicable, online ART was performed and gating on sagittal 2-dimensional cine MR was used. The charts of patients treated with MR-IGRT were reviewed to report on the clinical and treatment characteristics of the initial patients who were treated with this novel technique.

Results

A total of 316 patients have been treated with the MR-IGRT system, which has been integrated into a high-volume clinic. The cases were most commonly selected for improved soft tissue visualization, ART, and cine gating. Seventy-six patients were treated with 3-dimensional conformal radiation therapy, 146 patients with intensity modulated radiation therapy, and 94 patients with SBRT. The most commonly treated disease sites were the abdomen (28%), breast (26%), pelvis (22%), thorax (19%), and head and neck (5%). Sixty-seven patients were treated with online ART over a total of 244 adapted fractions. Cine treatment gating was used for a total of 81 patients.

Conclusions

MR-IGRT has been successfully implemented in a high-volume radiation clinic and provides unique advantages in the treatment of a variety of malignancies. Additional clinical trials are in development to formally evaluate MR-IGRT in the treatment of multiple disease sites with techniques such as SBRT and ART.

Quantitative FDG-PET/CT predicts local recurrence and survival for squamous cell carcinoma of the anus

Purpose

¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography–(PET)/computed tomography (CT) imaging is used for staging and treatment planning of patients with anal cancer. Quantitative pre- and posttreatment metrics that are predictive of recurrence are unknown. We evaluated the association between pre- and posttreatment FDG-PET/CT parameters and outcomes for patients with squamous cell carcinoma of the anus (SCCA).

Methods and materials

The records of 110 patients treated between 2003 and 2013 with definitive radiation therapy for SCCA were reviewed under an institutional review board–approved protocol. The median radiation therapy dose was 50.4 Gy (range, 35-60 Gy). Concurrent chemotherapy was administered for 109 of 110 patients and generally consisted of 5-fluorouracil and mitomycin C (n = 94). All patients underwent pretreatment FDG-PET/CT and 101 of 110 underwent posttreatment FDG-PET/CT 3 months after completion of radiation therapy. The maximum standard uptake value (SUV_max) was analyzed, in addition to multiple patient and treatment factors, by univariate and multivariate Cox regression for correlation with local recurrence (LR) and overall survival (OS).

Results

The median follow-up was 28.6 months. LR occurred in 1 of 15 (6.7%), 5 of 47 (10.6%), and 6 of 48 (12.5%) patients with stage I, II, and III disease, respectively. On univariate analysis, a significant association was observed between reduced LR and posttreatment SUV_max <6.1 (P = .0095) and between increased OS and posttreatment SUV_max <6.1 (P = .0086). On multivariate analysis, a significant association was observed between reduced LR and posttreatment SUV_max <6.1 (P = .0013) and the use of intensity modulated radiation therapy (P < .001). A significant multivariate association was observed between increased OS and posttreatment SUV_max <6.1 (P = .0373) and the use of 5-fluorouracil/mitomycin C chemotherapy (P = .001).

Conclusion

Posttreatment SUV_max <6.1 is associated with reduced LR and increased OS after chemoradiation therapy for SCCA independent of T and N stage on multivariate analysis. Greater follow-up is required to confirm this association with late patterns of failure.

Predictors of Radiation Therapy-Related Gastrointestinal Toxicity From Anal Cancer Dose-Painted Intensity Modulated Radiation Therapy: Secondary Analysis of NRG Oncology RTOG 0529

PURPOSE

NRG Oncology RTOG 0529 assessed the feasibility of dose-painted intensity modulated radiation therapy (DP-IMRT) to reduce the acute morbidity of chemoradiation with 5-fluorouracil (5FU) and mitomycin-C (MMC) for T2-4N0-3M0 anal cancer. This secondary analysis was performed to identify patient and treatment factors associated with acute and late gastrointestinal (GI) adverse events (AEs).

METHODS AND MATERIALS

NRG Oncology RTOG 0529 treatment plans were reviewed to extract dose-volume data for tightly contoured small bowel, loosely contoured anterior pelvic contents (APC), and uninvolved colon outside the target volume (UC). Univariate logistic regression was performed to evaluate association between volumes of each structure receiving doses ≥5 to 60 Gy (V5-V60) in 5-Gy increments between patients with and without grade ≥2 acute and late GI AEs, and grade ≥3 acute GI AEs. Additional patient and treatment factors were evaluated in multivariate logistic regression (acute AEs) or Cox proportional hazards models (late AEs).

RESULTS

Among 52 evaluable patients, grade ≥2 acute, grade ≥2 late, and grade ≥3 acute GI AEs were observed in 35, 17, and 10 patients, respectively. Trends (P<.05) toward statistically significant associations were observed between grade ≥2 acute GI AEs and small bowel dose (V20-V40), grade ≥2 late GI AEs and APC dose (V60), grade ≥3 acute GI AEs and APC dose (V5-V25), increasing age, tumor size >4 cm, and worse Zubrod performance status. Small bowel volumes of 186.0 cc, 155.0 cc, 41.0 cc, and 30.4 cc receiving doses greater than 25, 30, 35, and 40 Gy, respectively, correlated with increased risk of acute grade ≥2 GI AEs.

CONCLUSIONS

Acute and late GI AEs from 5FU/MMC chemoradiation using DP-IMRT correlate with radiation dose to the small bowel and APC. Such associations will be incorporated in the dose-volume normal tissue constraint design for future NRG oncology anal cancer studies.

Process improvement for the safe delivery of multidisciplinary-executed treatments-A case in Y-90 microspheres therapy

PURPOSE

To develop a safe and robust workflow for yttrium-90 (Y-90) radioembolization procedures in a multidisciplinary team environment.

METHODS AND MATERIALS

A generalized Define-Measure-Analyze-Improve-Control (DMAIC)-based approach to process improvement was applied to a Y-90 radioembolization workflow. In the first DMAIC cycle, events with the Y-90 workflow were defined and analyzed. To improve the workflow, a web-based interactive electronic white board (EWB) system was adopted as the central communication platform and information processing hub. The EWB-based Y-90 workflow then underwent a second DMAIC cycle. Out of 245 treatments, three misses that went undetected until treatment initiation were recorded over a period of 21 months, and root-cause-analysis was performed to determine causes of each incident and opportunities for improvement. The EWB-based Y-90 process was further improved via new rules to define reliable sources of information as inputs into the planning process, as well as new check points to ensure this information was communicated correctly throughout the process flow.

RESULTS

After implementation of the revised EWB-based Y-90 workflow, after two DMAIC-like cycles, there were zero misses out of 153 patient treatments in 1 year.

CONCLUSIONS

The DMAIC-based approach adopted here allowed the iterative development of a robust workflow to achieve an adaptable, event-minimizing planning process despite a complex setting which requires the participation of multiple teams for Y-90 microspheres therapy. Implementation of such a workflow using the EWB or similar platform with a DMAIC-based process improvement approach could be expanded to other treatment procedures, especially those requiring multidisciplinary management.

Preoperative short-course radiation therapy for rectal cancer provides excellent disease control and toxicity: Results from a single US institution

PURPOSE

Preoperative short-course radiation therapy (SCRT) has rarely been used for rectal cancer in the United States, although 2 randomized phase 3 trials demonstrate equivalence to conventional chemoradiation (CRT), and recent updates to national guidelines include this regimen as a treatment option. We sought to evaluate the efficacy and safety of preoperative SCRT followed by immediate surgery within 1 week to treat rectal cancer in the US setting.

METHODS AND MATERIALS

All patients treated with preoperative SCRT (4 Gy × 5 fractions for total 20 Gy) followed by planned surgery within 1 week at our institution were retrospectively evaluated. Censored cases with ≥2 years of follow-up were included along with any disease failure or death. Patients with cM1 disease were excluded. Patients with yp stage II/III disease typically received adjuvant chemotherapy from the 1990s onwards. The primary outcomes were actuarial (Kaplan-Meier) 5-year locoregional control (LC), disease-free survival (DFS), and overall survival (OS) as well as late severe (greater than or equal to grade 3) toxicity.

RESULTS

Our analysis included 202 consecutive patients with clinical stage I-III disease treated from 1977 through 2011. Median follow-up was 6.5 years (range, 2-29.2). Five-year disease outcomes were 95.9% ± 1.5% for LC, 76.4% ± 3.1% for DFS, and 84.6% ± 2.6% for OS. For patients with locally advanced rectal cancer (cT3-4 and/or cN+), 5-year LC, DFS, and OS were 95.1% ± 2.1%, 73.3% ± 4.3%, and 80.6% ± 3.7%, respectively. The late severe toxicity rate was 11.4%.

CONCLUSIONS

SCRT followed by immediate surgery is a safe and effective treatment for patients with rectal cancer in the United States. Though SCRT has not been widely adopted, recent updates to the national guidelines for rectal cancer as well as financial pressures to reduce healthcare costs may lead to increased utilization of this treatment regimen in the future.

Quality of life impact of childhood skin conditions measured using the Children's Dermatology Life Quality Index (CDLQI): a meta-analysis

BACKGROUND

The Children's Dermatology Life Quality Index (CDLQI) is the most widely used instrument for measuring the impact of skin disease on quality of life (QoL) in children.

OBJECTIVES

To provide a meta-analysis of all published QoL scores for a range of childhood skin conditions.

METHODS

Studies using the CDLQI questionnaire to measure QoL in skin conditions were identified by searching Medline and Embase from January 1995 (CDLQI creation) to December 2014. Studies were grouped according to condition and baseline scores were combined using meta-analysis.

RESULTS

Sixty-seven studies using the CDLQI met the inclusion criteria. The overall estimated CDLQI scores for conditions reported more than once were [point estimate (95% confidence interval, CI), number of studies (n), score range]: atopic eczema [8·5 (7·1-9·8), n = 38, 0-29], acne [5·3 (1·9-8·5), n = 5, 0-30], alopecia [3·1 (0-7·7), n = 2, 0-6], molluscum contagiosum [3·5 (0·6-6·7), n = 5, 0-27], psoriasis [8·0 (3·9-12·1), n = 6, 0-29], scabies [9·2 (0·0-20·3), n = 2, 1-26], urticaria [7·1 (0-15·4), n = 2, 0-22], vitiligo [6·5 (0·7-12·2), n = 2, 0-20] and warts [2·9 (0-5·8), n = 4, 0-16]. Overall, the mean effect on QoL [weighted average CDLQI score 4·6 (95% CI 3·9-5·4)] for children with these conditions was small. However, many children were found to experience a very large impact on QoL (34% of children with atopic eczema, 10% with molluscum contagiosum and 1-5% with acne) in studies where the distributions of scores were provided.

CONCLUSIONS

Most skin conditions in children have a 'small' mean effect on QoL. However, the range is large and a significant proportion of children with many common skin conditions will experience a very large effect on quality of life.

Prospective phase I study of nab-paclitaxel plus gemcitabine with concurrent MR-guided IMRT in patients with locally advanced or borderline resectable pancreatic cancer

TPS480

Background: Radiotherapy (RT) for locally advanced and borderline resectable pancreatic cancer (LABPC) is controversial as potential local control benefits are often obscured by high rates of distant progression. However, local failure remains a significant cause of morbidity among patients without distant progression after initial chemotherapy, although toxicity concerns may limit delivery of optimal systemic therapy concurrent with RT. Given known systemic efficacy and radiosensitization effects of nab-paclitaxel (A) with gemcitabine (G), we initiated a phase I study of nab-paclitaxel with gemcitabine (AG) and concurrent intensity modulated radiation therapy with magnetic resonance guidance (MR-IMRT) for LABPC. Methods: A planned 24 patients with LABPC will be enrolled to a phase I dose escalation trial using the Time-to-Event Continual Reassessment Method (TITE-CRM) design. Following one lead-in cycle of GA, MR-IMRT is administered daily with concurrent weekly GA for a total of 25 fractions in 5 weeks. The initial dose levels for RT and AG, respectively, are: 40 Gy MR-IMRT, 75 mg/m2 A and 600mg/m2 G. The maximum possible dose level is 60 Gy MR-IMRT, 100mg/m2 A and 1000mg/m2 G. To reduce toxicity risk, MR-IMRT volumes include the primary tumor only, with cine-MR used for intra-fraction tumor tracking in place of fiducial markers. The primary endpoint is determination of the maximum tolerated dose level, with secondary endpoints including rate of conversion to resectable disease, progression- free survival, overall survival, and patient reported quality of life. Clinical trial information: NCT02283372.

Utility of a multidisciplinary tumor board in the management of pancreatic diseases

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Background: Multidisciplinary Tumor Boards (MTBs) are a requirement for comprehensive cancer centers and are routinely used to coordinate multidisciplinary care in oncology. Despite their widespread use, the impact of MTBs is not well characterized. We studied the outcomes of all patients presented at our pancreas MTB, with the goal of evaluating our current practices and resource utilization. Methods: Data were prospectively collected for all patients presented at a weekly pancreas-specific MTB over the 12-month period at a single-institution NCI-designated cancer center. The conference is attended by surgical, medical, and radiation oncologists, interventional gastroenterologists, pathologists, and radiologists (diagnostic and interventional). Retrospective chart review was performed at the end of the 12-month period under an IRB-approved protocol. Results: A total of 470 patient presentations were made over a 12-month period. Average age at time of presentation was 61.5 years (range 17 – 89) with 51% males. 61.7% of cases were presented by surgical oncologists and 26% by medical oncologists. 174 cases were the result of new diagnoses or referrals. 78 patients were presented more than once (average of 2.3 times). Pancreatic adenocarcinoma was the most common diagnosis (37%), followed by uncharacterized pancreatic mass (16%), and pancreatic cyst (7%). The treatment plan proposed by the presenting clinician was known or could be evaluated prior to conference in 402 cases. Presentation of a case at MTB changed the plan of management 25% (n = 100) of the time, including MTB recommendation against a planned resection in 46 cases. When the initial plan changed as a result of MTB discussion, the most common new plan was to obtain further diagnostic testing such as biopsy and/or endoscopy (n = 24). Conclusions: MTBs are required and resource-intensive but offer the opportunity to discuss a wide array of pathologies and influence management decisions in a sizable proportion of cases. Additional investigations evaluating adherence rates to MTB decisions and to published guidelines (i.e. National Comprehensive Cancer Network) will further enhance the assessment and utility of MTBs.

Late gastrointestinal tissue effects after hypofractionated radiation therapy of the pancreas

BACKGROUND

To consolidate literature reports of serious late gastrointestinal toxicities after hypofractionated radiation treatment of pancreatic cancer and attempt to derive normal tissue complication probability (NTCP) parameters using the Lyman-Kutcher-Burman model.

METHODS

Published reports of late grade 3 or greater gastrointestinal toxicity after hypofractionated treatment of pancreatic cancer were reviewed. The biologically equivalent dose in 1.8 Gy fractions was calculated using the EQD model. NTCP parameters were calculated using the LKB model assuming 1-5% of the normal tissue volume was exposed to the prescription dose with α/β ratios of 3 or 4.

RESULTS

A total of 16 human studies were examined encompassing a total of 1160 patients. Toxicities consisted of ulcers, hemorrhages, obstructions, strictures, and perforations. Non-hemorrhagic and non-perforated ulcers occurred at a rate of 9.1% and were the most commonly reported toxicity. Derived NTCP parameter ranges were as follows: n = 0.38-0.63, m = 0.48-0.49, and TD50 = 35-95 Gy. Regression analysis showed that among various study characteristics, dose was the only significant predictor of toxicity.

CONCLUSIONS

Published gastrointestinal toxicity reports after hypofractionated radiotherapy for pancreatic cancer were compiled. Median dose was predictive of late grade ≥ 3 gastrointestinal toxicity. Preliminary NTCP parameters were derived for multiple volume constraints.

Comparison of onboard low-field magnetic resonance imaging versus onboard computed tomography for anatomy visualization in radiotherapy

BACKGROUND

Onboard magnetic resonance imaging (OB-MRI) for daily localization and adaptive radiotherapy has been under development by several groups. However, no clinical studies have evaluated whether OB-MRI improves visualization of the target and organs at risk (OARs) compared to standard onboard computed tomography (OB-CT). This study compared visualization of patient anatomy on images acquired on the MRI-(60)Co ViewRay system to those acquired with OB-CT.

MATERIAL AND METHODS

Fourteen patients enrolled on a protocol approved by the Institutional Review Board (IRB) and undergoing image-guided radiotherapy for cancer in the thorax (n = 2), pelvis (n = 6), abdomen (n = 3) or head and neck (n = 3) were imaged with OB-MRI and OB-CT. For each of the 14 patients, the OB-MRI and OB-CT datasets were displayed side-by-side and independently reviewed by three radiation oncologists. Each physician was asked to evaluate which dataset offered better visualization of the target and OARs. A quantitative contouring study was performed on two abdominal patients to assess if OB-MRI could offer improved inter-observer segmentation agreement for adaptive planning.

RESULTS

In total 221 OARs and 10 targets were compared for visualization on OB-MRI and OB-CT by each of the three physicians. The majority of physicians (two or more) evaluated visualization on MRI as better for 71% of structures, worse for 10% of structures, and equivalent for 14% of structures. 5% of structures were not visible on either. Physicians agreed unanimously for 74% and in majority for > 99% of structures. Targets were better visualized on MRI in 4/10 cases, and never on OB-CT.

CONCLUSION

Low-field MR provides better anatomic visualization of many radiotherapy targets and most OARs as compared to OB-CT. Further studies with OB-MRI should be pursued.

Perioperative Therapy for Surgically Resectable Pancreatic Adenocarcinoma

It is estimated that 10% to 20% of patients with pancreatic cancer present with resectable disease. Although surgery offers curative intent, the median survival after curative resection is less than 2 years. To improve clinical outcomes in this patient population, clinical studies have investigated the role of perioperative therapy, including neoadjuvant and adjuvant treatment in resectable pancreatic cancer. The role of adjuvant therapy has been well established by large randomized phase III studies, whereas benefit of the neoadjuvant approach remains inconclusive. Here, we review various treatment modalities and their clinical benefits in resectable pancreatic cancer.

Retroperitoneal Sarcoma Target Volume and Organ at Risk Contour Delineation Agreement Among NRG Sarcoma Radiation Oncologists

PURPOSE

The purpose of this study was to evaluate the variability in target volume and organ at risk (OAR) contour delineation for retroperitoneal sarcoma (RPS) among 12 sarcoma radiation oncologists.

METHODS AND MATERIALS

Radiation planning computed tomography (CT) scans for 2 cases of RPS were distributed among 12 sarcoma radiation oncologists with instructions for contouring gross tumor volume (GTV), clinical target volume (CTV), high-risk CTV (HR CTV: area judged to be at high risk of resulting in positive margins after resection), and OARs: bowel bag, small bowel, colon, stomach, and duodenum. Analysis of contour agreement was performed using the simultaneous truth and performance level estimation (STAPLE) algorithm and kappa statistics.

RESULTS

Ten radiation oncologists contoured both RPS cases, 1 contoured only RPS1, and 1 contoured only RPS2 such that each case was contoured by 11 radiation oncologists. The first case (RPS 1) was a patient with a de-differentiated (DD) liposarcoma (LPS) with a predominant well-differentiated (WD) component, and the second case (RPS 2) was a patient with DD LPS made up almost entirely of a DD component. Contouring agreement for GTV and CTV contours was high. However, the agreement for HR CTVs was only moderate. For OARs, agreement for stomach, bowel bag, small bowel, and colon was high, but agreement for duodenum (distorted by tumor in one of these cases) was fair to moderate.

CONCLUSIONS

For preoperative treatment of RPS, sarcoma radiation oncologists contoured GTV, CTV, and most OARs with a high level of agreement. HR CTV contours were more variable. Further clarification of this volume with the help of sarcoma surgical oncologists is necessary to reach consensus. More attention to delineation of the duodenum is also needed.

Pretreatment diffusion weighted imaging for clinical outcome assessment in patients undergoing definitive chemoradiation for pancreatic adenocarcinoma

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Background: Factors predicting patterns of failure for pancreatic ductal adenocarcinoma (PDA) are not well-established. Diffusion-weighted MRI (DWI) is useful in predicting recurrence for other gastrointestinal malignancies. The purpose of this study was to evaluate for correlation between tumor DWI parameters and clinical outcomes following chemoradiotherapy (CRT) for pancreatic adenocarcinoma. Methods: From 2009 to 2013, 27 patients with locally advanced (n=14), borderline resectable (n=12) or resectable (n=1) PDA underwent CRT. All patients received upfront FOLFIRINOX or gemcitabine-based chemotherapy prior to CRT, and gemcitabine (median weekly dose 800 mg/m2) concurrent with radiotherapy. DWI was obtained during radiotherapy treatment planning, and apparent diffusion coefficient (ADC) maps were generated to allow determination of median tumor ADC. Tumor-directed CRT was administered with respiratory gated intensity modulated radiation therapy, 55Gy in 25 fractions without elective nodal coverage. Patients were followed by imaging every 2-3 months. Log rank test was used to estimate an optimal ADC cut-point of 1.4*10-3mm2/sec based on distant metastasis free survival (DMFS) and overall survival (OS). Analysis of local recurrence was not performed due to limited events. The log-rank test was used to evaluate differences in outcome between groups based on ADC classification. Results: The median time to last follow-up from completion of CRT was 9.7 months for all patients and 11 months among living patients. 5 patients underwent resection following CRT. The 1-year DMFS for patients with median ADC<1.4*10-3mm2/sec was 79.5 percent, compared to 47.6 percent for those with median ADC >1.4. The 1-year OS for patients with median ADC<1.4 was 100 percent, compared to 46.3 percent for those with median ADC >1.4. Both DMFS (p=.041) and OS (p=.003) were significantly improved on log-rank test for ADC<1.4 compared to ADC>1.4. Conclusions: A correlation was observed between DWI parameters and clinical outcomes for PDA. Further prospective study should be explored to validate DWI as a prognostic imaging biomarker.

Matched pair analysis of sequential short course radiotherapy and FOLFOX chemotherapy as preoperative therapy for rectal cancer compared to neoadjuvant long course chemoradiotherapy

665

Background: A recently completed institutional phase II trial evaluated near-total neoadjuvant therapy (nTNT) for locally advanced rectal cancer using short course radiotherapy (SCRT) followed by four cycles of FOLFOX prior to total mesorectal excision (TME). A matched pair analysis is presented to compare clinical outcomes for nTNT with conventional chemoradiotherapy (CRT), TME, and postoperative chemotherapy (CT) for patients treated at our institution. Methods: 80 patients with cT3-4N0-2M0-1 rectal adenocarcinoma planned for resection of all tumor enrolled on a phase II study of preoperative SCRT (25 Gy to the involved mesorectum, 20 Gy to elective nodes, in 5 fractions) followed by four cycles of mFOLFOX6 before TME, with 6-8 cycles of adjuvant FOLFOX suggested. 69 patients with cM0 disease comprised the study cohort for this analysis. Patients treated with conventional CRT, followed by TME and adjuvant CT (63% ≥4 cycles adjuvant FOLFOX) were identified and matched 2:1 for exact cTNM stage. Kaplan-Meier with log-rank analysis was used to compare local control (LC), distant metastasis free survival (DMFS), disease free survival (DFS), and overall survival (OS), and two-tailed Mann-Whitney and Chi-squared tests used to compare cohort characteristics. Results: Median follow-up was 26 and 49 months for the study and control groups, respectively. Median age (57 vs. 55 years, p = 0.98) and distance from the anorectal ring (6 vs. 5 cm, p = 0.16) were similar for study and control groups, respectively. Pathologic complete response (pCR) and T-downstaging rates were 30% vs. 23% (p = 0.26) and 75% vs 50% (p = 0.001) in the study and match cohort, respectively. Actuarial 2-year LC (97% vs. 98%, p = 0.69) and OS (100% vs. 95% at 2 years, p = 0.57) were similar between the study and control groups, respectively. Two-year DMFS (94% vs. 80%, p = 0.016) and DFS (94% vs. 80%, p = 0.027) were significantly better in the study cohort. Conclusions: Controlling for institutional bias, exact cTNM stage, and tumor location, nTNT resulted in increased T-downstaging, superior DMFS and DFS, and similar LC and OS compared to conventional CRT.

Predictors of radiotherapy-related gastrointestinal toxicity from anal cancer DP-IMRT: Secondary analysis of RTOG 0529

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Background: Radiation Therapy Oncology Group (RTOG) 0529 assessed feasibility of dose-painted intensity-modulated radiation therapy (DP-IMRT) to reduce the acute morbidity of chemoradiation with 5-fluorouracil (5FU) and mitomycin-C (MMC) for T2-4N0-3M0 anal cancer. This secondary analysis was performed to identify patient (pt) and treatment factors associated with acute and late gastrointestinal (GI) adverse events (AEs). Methods: RTOG 0529 treatment plans were reviewed to extract dose-volume data for tightly contoured small bowel (SB), loosely contoured anterior pelvic contents (APC), and uninvolved portions of colon outside the clinical target volume (UC). T-tests were performed to evaluate differences in the mean absolute volumes of each critical structure receiving doses ≥ 5 to 60 Gy (V5-V60) in 5 Gy increments between pts with and without ≥ grade (G) 2, acute and late GI AEs, and ≥G3 acute GI AEs using the NCI Common Terminology Criteria, version 3. Acute is defined as ≤ 90 days from the start of treatment and late is > 90 days. Additional factors (age, location, gender, race, Zubrod, grade, size, stage, prone vs supine position) were also evaluated in multivariate (MV) logistic regression (acute AEs) or Cox proportional hazards models (late AEs) to evaluate correlation with GI AEs. Results: Among 52 evaluable pts, ≥G2 acute, ≥G2 late, and ≥G3 acute GI AEs were observed in 35, 17, and 10 pts, respectively. Trends (p<0.05) towards statistically significant associations were observed between: ≥G2 acute GI AEs and SB dose (V20-V40); ≥G2 late GI AEs and APC dose (V60); ≥G3 acute GI AEs and APC dose (V5-V25), increasing age, tumor size >4cm, and worse Zubrod. SB and APC dose parameters remained correlated with GI AEs on MV analysis. Treatment in the prone vs supine position correlated with lower SB V10-V35 and APC V5-V20, although no significant differences in GI AEs were observed. Conclusions: Acute and late GI AEs from 5FU/MMC chemoradiation using DP-IMRT correlates with RT dose to the SB and APC. Further analysis is underway to determine critical structure cut-point parameters that may aid treatment plan optimization for anal cancer DP-IMRT. Supported by RTOG U10 CA21661, CCOP U10 CA3742 and ATC U24 CA 81647 NCI grants. Clinical trial information: NCT00423293.

Stereotactic body radiation therapy for the treatment of early-stage minimally invasive adenocarcinoma or adenocarcnioma in situ (formerly bronchioloalveolar carcinoma): a patterns of failure analysis

Introduction

Ongoing prospective trials exploring stereotactic body radiation therapy (SBRT) for early stage non-small cell lung cancer (NSCLC) often exclude minimally invasive adenocarcinoma or adenocarcnioma in situ, formerly bronchioloalveolar carcinoma (BAC), due to concerns for accurate target delineation on CT. We performed a patterns of failure analysis to compare outcomes between BAC and other NSCLC subtypes.

Methods

One hundred twenty patients with early stage NSCLC were treated with SBRT from 2004–2009. Pathologic confirmation of NSCLC was obtained in 97 patients. Radiotherapy was delivered according to RTOG guidelines. The log-rank test was used to compare outcomes between BAC and other NSCLC.

Results

Median follow-up was 29 months. The median SBRT dose was 5400 cGy. Thirteen patients had radiographically diagnosed BAC and five patients had biopsy confirmed BAC, of which two had both. The three-year local control was 100% for biopsy-proven or radiographically diagnosed BAC (n = 18) and 86% for all other NSCLC subtypes (n = 102) (p = 0.13). Likewise, no significant difference was detected between BAC and other NSCLC for 3-year regional failure (12% vs. 20%, p = 0.45), progression-free survival (57.6% vs. 53.5%, p = 0.84) or overall survival (35% vs. 47%, p = 0.66). There was a trend towards lower three-year rates of freedom from distant failure in patients with any diagnosis of BAC compared to those without (26% vs. 38%, p = 0.053).

Conclusions

Compared to other NSCLC subtypes, BAC appears to have similar patterns of failure and survival after treatment with SBRT, however there may be an increased risk of distant metastases with BAC. RTOG guideline-based target delineation provides encouraging local control rates for patients with BAC.

Tumor volume and subvolume concordance between FDG-PET/CT and diffusion-weighted MRI for squamous cell carcinoma of the cervix

PURPOSE

To compare [(18)F]fluorodeoxyglucose (FDG)/positron emission tomography (PET)/computed tomography (CT) and magnetic resonance imaging (MRI) for evaluating patients with cervical cancer. We compared tumor characteristics on FDG-PET and apparent diffusion coefficient (ADC) maps on diffusion-weighted MRI (DWI) to evaluate concordance of two functional imaging techniques.

MATERIALS AND METHODS

Twenty women with cervical cancer underwent pretreatment FDG-PET/CT and pelvic MRI. Images were rigidly fused by pelvic anatomy using coregistration software. Tumor contours on PET images were generated by autosegmentation of the region containing at least 40% of the maximum standardized uptake value (SUV). DWI contours were generated by manual segmentation. Tumor volume similarity was evaluated using the [PET]/[ADC] volume proportion, Dice's coefficient, and the mean SUV isothreshold at the surface of each ADC contour. Tumor subvolume similarity was evaluated with analysis of variance (ANOVA).

RESULTS

The [PET]/[ADC] volume proportion was 0.88 ± 0.14. Dice's coefficient between PET and ADC tumor contours was 0.76 ± 0.06. The mean SUV isothreshold at the ADC-delineated tumor surface was 34 ± 4%. Subvolumes with increased metabolic activity on FDG-PET also had more restricted diffusion on DWI (P < 0.0001, ANOVA).

CONCLUSION

Concordance of functional imaging was observed between FDG-PET and DWI for cervical cancer. Tumor subvolumes with increased metabolic activity on FDG-PET also have greater cell density by DWI.