Outcomes of Cytoreductive Stereotactic Body Radiotherapy (SBRT) in Patients with Oligometastatic or Oligoprogressive Dominant Lung Metastases from Colorectal Primary

PURPOSE/OBJECTIVE(S)

Oxaliplatin based systemic therapy regimens have improved the prognosis of patients with colorectal cancer (CRC) and with this, there has been increased interest in the integration of local therapies to oligometastatic and oligoprogressive sites. There is a vast body of literature exploring the benefits of cytoreduction with surgery and stereotactic body radiation therapy (SBRT) approaches. We report our rates of local control (LC) and overall survival (OS) for patients with oligometastatic/progressive CRC with lung metastases treated with SBRT.

MATERIALS/METHODS

Single institution retrospective review of patients diagnosed with oligometastatic or oligoprogressive CRC with dominant metastases to the lungs who were treated with SBRT between September 2009 and December 2022. Oligometastatic disease was defined as newly diagnosed, untreated CRC with up to 5 metastases, up to 3 in one organ. Oligoprogressive disease was defined as CRC with 1 - 2 distant sites that continued to progress on active treatment while the primary site was controlled. Survival was estimated using Kaplan-Meier. Association between local control and patient factors was analyzed using log-rank test.

RESULTS

A total of 84 patients with oligometastatic or oligoprogressive CRC were treated with SBRT to 124 lung lesions. Colon cancer was the primary site for 54 patients with a median age at time of SBRT of 66 years (IQR 57 - 73) and a median tumor diameter of 1.20 cm (IQR 0.93 - 1.90). Rectal cancer was the primary site for 30 patients, median age was 60 years (IQR 49 - 70) and median tumor diameter was 1.10 cm (IQR 0.80 - 1.48). Median dose for the entire cohort was 6000 cGy (range 5000 - 6000) with median number of fractions 5 (range 3 - 5). Median follow-up after SBRT was 24 months. Overall, there were 9 local failures at last follow-up. Almost half (n = 42) of the patients experienced distant recurrence. Median local control (LC) for the entire cohort was not reached, 2-yr LC and 5-yr LC were 94.6% and 85.7% respectively. There were no differences in LC between colon and rectal cancer (p = 0.29). Actuarial median overall survival was 71 months (95% CI 44.3 - 97.7) and 5-yr OS was 50.2%. Due to the small number of events, we were unable to identify patient factors associated with local failure on univariate or multivariate analysis.

CONCLUSION

Cytoreductive SBRT is an effective treatment option for patients with oligometastatic or oligoprogressive CRC with dominant lung metastases offering excellent rates of LC. Most patients failed distantly highlighting the importance of additional systemic therapies.

Adrenal Stereotactic Body Radiation Therapy: Do Dosimetric Factors Predict for Grade 2+ Lymphopenia?

PURPOSE/OBJECTIVE(S)

Recent studies suggest improvement in outcomes in multiple oligometastatic tumor sites with immunotherapy (IO) and radiation therapy (RT). However, RT may induce lymphopenia that can be immunosuppressive and dosimetric consensus is lacking on parameters predicting grade ≥2 lymphopenia. In this study, we evaluated lymphopenia post receipt of stereotactic body RT (SBRT) for adrenal metastases to see if we could identify any modifiable treatment planning factors.

MATERIALS/METHODS

Patients with adrenal oligometastases who were treated with conventional SBRT or MRI-guided (MRgSBRT), had absolute lymphocyte count (ALC) and white blood cell count (WBC) data available within 6 weeks before and after their radiation treatment, and had contouring data available for review were included in this IRB approved retrospective study. Lymphopenia was graded for ALC as: Grade 1 (1.0-0.8 no/ul), Grade 2 (<0.8 - 0.5 no/ul), Grade 3 (<0.5-0.2 no/ul), Grade 4 (<0.2 no/ul). The vertebral bodies (VB), at the level of the planning treatment volume (PTV) and one above and below, and the spleen were contoured. Dosimetric variables of interest included spleen and VB mean dose (Gy) as well as V2.5-20 Gy in 2.5 Gy increments. Regression analyses were used to identify dosimetric variables associated with absolute and relative difference in ALC post-SBRT.

RESULTS

A total of 30 patients were identified with a slight male predominance (N = 17, 57%) and most commonly left adrenal (N = 17) versus right adrenal (N = 10, 33%) or bilateral metastases (N = 3, 10%). Grade 2+ lymphopenia was observed in N = 7 patients pre-SBRT (23%) and N = 17 patients post-SBRT (57%). N = 26 (87%) of the patients had previous chemotherapies and N = 17 (57%) had previous immunotherapy. Multiple primary tumor types were represented with the most common non-small cell lung cancer (N = 14, 47%), followed by melanoma (N = 4, 13%) and small cell lung cancer (N = 3, 10%). Most patients were treated with non-MRgSBRT (N = 19, 63%) vs MRgRT (N = 11, 37%) and all received SBRT in 5 fractions with median dose 50 Gy (Range: 25 - 60 Gy). The median pre-SBRT ALC was 1.13 (Range: 0.39 - 2.96) and median post-SBRT ALC was 0.72 (Range: 0.11 - 4.15). On linear regression analysis, there was no significant association between post SBRT ALC nor lymphopenia grade with splenic or vertebral body dose, treatment laterality, or SBRT dose.

CONCLUSION

In this retrospective series of predominately metastatic lung cancer patients treated with adrenal SBRT, we observed high rates of post SBRT grade 2+ lymphopenia, yet no dosimetric parameter was predictive, not even for left-sided lesions. Future work includes clinical validation of these findings in a larger population, likely with multi-institutional collaboration, and further study of the investigation of the IO/RT sequencing issues in such heavily pre-treated patients.

Borderline Resectable Pancreatic Cancer: Impact on Neoadjuvant Response Post Integration of MRI Guided Adaptive Radiation Therapy

PURPOSE/OBJECTIVE(S)

The optimal neoadjuvant therapy regimen for patients with borderline resectable pancreas cancer (BRPC) remains to be defined, with a recent ALLIANCE study reporting that chemotherapy alone prior to resection is an acceptable standard of care. However, pathologic differences in response between patients receiving chemotherapy alone and chemotherapy with radiation with stereotactic technique is not clear. In this study, we sought to compare differences in pathologic outcomes between patients undergoing surgery in 2018 compared with 2021 at our comprehensive cancer center, after the new data of chemotherapy alone had been reported and after our center integrated stereotactic MRI guided online adaptive radiotherapy (SMART).

MATERIALS/METHODS

Newly diagnosed BRPC patients were included on this IRB approved study if they were treated on our institutional clinical pathway with initial chemotherapy (FOLFIRINOX or Gemcitabine based) followed by 5 fraction stereotactic body radiation therapy (SBRT) with the intention of primary tumor resection. After surgical resection, tumor response was classified by the Tumor Regression Grading (TRG) System of the College of American Pathology on a scale from 0 (complete response) to 3 (poor response).

RESULTS

In 2018 when patients were treated on a conventional Linac, the median SBRT dose was 40.5 Gy compared with 46.1 Gy in 2021 after SMART integration. In 2018, 54 BRPC patients were treated and 52% were explored. Of those, 72% were resected with a 95% (19/20) rate of R0 resection. In 2021, 66 BRPC patients were treated and 45% were explored. Of those, 74% were resected with a 100% (22/22) rate of R0 resection. In 2018, pathological results showed that 55% (11/20) had lymphovascular invasion (LVI) and 90% (18/20) had perineural invasion (PNI) with a median tumor size of 2.5 cm. The average lymph node ratio in 2018 was 0.06 in 2018 and 0.05 in 2021. In 2021, pathological results showed that 36% (8/22) had LVI and 64% (14/22) had PNI with a median tumor size of 2.2 cm. In 2018, 43% of surgeries required portal vein (PV) resection compared with 27% in 2021. In 2018, of those patients who underwent surgery, 65% (13/20) received both chemotherapy and SBRT compared to 10% (2/20) with chemotherapy alone. In 2021, 73% (16/22) received chemotherapy and SBRT prior to surgery compared with 27% (6/22) who received chemotherapy only. Patients who received chemotherapy only (n = 8) had an average TRG of 2.1 compared to the patients receiving combination therapy (29) with an average TRG of 1.8.

CONCLUSION

This data suggests that higher ablative dose delivery with SMART following systemic therapy may be associated with improved pathologic outcomes, with less LVI, PNI, portal vein resection and improved TRG scores. Further prospective study is needed to confirm improved pathologic outcomes with SMART and to optimize patient selection regarding which patients benefit the most from the combination of chemotherapy and SBRT.

Pancreas Cancer Learning Health Network Established to Share Best Practice Across 14 Centers and Improve Patient Outcomes

PURPOSE/OBJECTIVE(S)

Pancreas cancer (PC) survival is among the lowest of all malignancies. Clinical trials have failed to significantly improve outcomes. Individual and institutional biases in care result in significant variation in practice, further hindering progress. Learning health networks (LHNs) prospectively collect real world data across centers and test improvements that can rapidly be expanded across centers if deemed successful. Herein, we report preliminary progress from the Pancreas Cancer Canopy Cancer Collective (PC-CCC), the first oncology LHN, established to improve duration and quality of survival in PC.

MATERIALS/METHODS

In 2019, we established the PC-CCC with six care centers who engaged in a collaborative design process to create a set of improvement aims, change ideas, and outcome measures. Center team members receive training and coaching in collaborative quality improvement methods, applied to local improvement efforts. Eight more centers joined in 2021, and a shared Canopy outcomes database was built and implemented to inform center-specific and network-wide improvement efforts and allow the LHN to undertake research using real-world data. Current improvement efforts are focused on proactively screening new PC patients for: (1) Clinical trials, (2) pancreas enzymes, (3) palliative care needs, and (4) goals of care conversations.

RESULTS

Currently, 14 care centers are active participants in the PC-CCC LHN. Data on a total of 2,002 PC patients are available to date. At presentation to the care center, most patients are female (51%) and have biopsy proven PC (83.9%). Average age is 68 years, and presenting disease status is metastatic (14.5%), resectable (11.4%), locally advanced (10.9%), borderline resectable (8.1%), or not yet staged (40%). For those who received radiation, 75.8% received stereotactic body radiation therapy. Among patients whose chemotherapy regimen was documented, most received 5-fluorouracilbased treatment (52%). Descriptive follow up data (including treatment and outcomes) are being actively updated, to be reported at time of presentation.

CONCLUSION

Creation of a cancer LHN for PC is feasible and has set the stage for improving patient and provider outcomes through iterative community-building, continuous improvement, and sharing of data and multidisciplinary best practices. Additionally, the data obtained from the CCC database can rapidly inform the network how variation in clinical practice across centers can influence outcomes.

Toward Burnout Prevention: Can One Short Virtual Reality Relaxation and Mindfulness Training Session for Staff and Patients Decrease Stress and Improve Subjective Sense of Wellbeing?

PURPOSE/OBJECTIVE(S)

Mental wellness of healthcare workers has deteriorated recently, increasing burnout rates. Cancer patients are also often highly distressed, reporting fear, pain, and fatigue. Relaxation and mindfulness training have been shown to decrease stress and anxiety. Currently, the use of virtual reality (VR) for relaxation and mindfulness for cancer patients and oncology clinical staff is an ongoing area of research. We aimed to test the preliminary efficacy of incorporating an innovative digital therapeutic (DTx) we developed at our center in this population.

MATERIALS/METHODS

Cancer patients and clinic staff from one institution's Gastrointestinal and Radiation Oncology departments participated in the immersive VR-enhanced relaxation and mindfulness experience for this IRB-exempt study. Users completed a pre-VR survey via iPad assessing baseline knowledge and practice of stress reduction techniques, baseline stress, and familiarity with VR. In the VR app deployed on an Oculus Quest 2, users chose a relaxing water scene (e.g., stream, beach) and optional soothing background music. Users could also choose a relaxation or mindfulness training audio track. A post-VR survey assessed whether the experience affected their subjective stress and sense of wellbeing ("Yes" or "No") as well as the feasibility of using the app. A binomial test on a single proportion was used to test whether more participants (>50%) indicated their stress was reduced following the VR training than did not. Post-VR qualitative verbal feedback was also collected to identify future changes to the VR app.

RESULTS

Six patients, a patient's son, and forty-three employees used the VR app. Users were aged ≤ 30 years old (18%), 30-50 years (60%), and 50-70 years (22%). Users completed the VR experience in a median of 14 min (IQR: 11-19 min). In the pre-survey, most (78%) reported they felt stress at this point in their lives. In the post-survey, significantly more than the expected proportion of participants (>50%) reported feeling less stressed after using the VR app (88%, n = 44, p <0.001). Most (90%) reported that the VR app improved their subjective sense of wellbeing. All (100%) users reported it was easy to learn the VR controls. Nearly all (96%) reported they would be interested in using this VR app again, including 30% and 38% who reported they would be "extremely likely" and "very likely," respectively, to use the app again.

CONCLUSION

These findings suggest our VR relaxation and mindfulness training was well accepted and could be integrated into the hospital setting in short sessions. Further work should be done based on participant feedback to expand the offerings of this VR app to offer a wider range of relaxation experiences and gamified psychological interventions that can help de-stress, recharge, and build resiliency.

Synchronous rectal adenocarcinoma and splenic marginal zone lymphoma

Synchronous cancers of different primary origin are rare. Here, we describe the case of a patient with concomitant diagnoses of rectal adenocarcinoma and splenic marginal zone lymphoma (smzl). A 57-year-old woman initially presented with abdominal pain. Physical examination and computed tomography demonstrated massive splenomegaly, and a complete blood count revealed microcytic anemia and lymphopenia. During the subsequent evaluation, she presented with hematochezia, melena, and constipation, which prompted gastroenterology referral. Subsequent endoscopic rectal ultrasonography revealed a T3N1 moderately differentiated rectal adenocarcinoma, with computed tomography imaging of chest, abdomen, and pelvis confirming no metastasis. Thus, the cancer was classified as clinical stage T3N1M0, stage iii. Bone marrow biopsy confirmed co-existing marginal zone lymphoma, and with the clinical presentation of massive splenomegaly, a diagnosis of smzl was made. The patient's management was individually tailored for simultaneous optimal treatment of both conditions. Concurrent treatment with neoadjuvant rituximab and 5-fluorouracil chemotherapy, with external-beam radiation therapy to the pelvis, was administered, followed by surgery consisting of en bloc splenectomy and distal pancreatectomy, and low anterior resection. The patient completed a standard course of adjuvant folfox (fluorouracil-leucovorin-oxaliplatin) chemotherapy and has remained disease-free for 7 years. To our knowledge, this report is the first to specifically describe simultaneous diagnoses of locally advanced rectal cancer and smzl. We also describe the successful combined neoadjuvant treatment combination of 5-fluorouracil, rituximab, and pelvic radiation.

Carboplatin and paclitaxel as first-line treatment of unresectable or metastatic esophageal or gastric cancer

Survival in patients with metastatic esophageal and gastric cancer is dismal. No standard treatment has been established. Carboplatin/paclitaxel is active in both advanced gastric and esophageal cancer. Here we retrospectively present our single center experience. Between 1998 and 2013, a total of 134 patients with metastatic esophageal and gastric adenocarcinoma treated with carboplatin/paclitaxel (carboplatin predominantly area under the curve 5 and paclitaxel predominantly 175 mg/m(2)) every 3 weeks as first-line therapy were identified. Baseline characteristics, response to therapy, toxicities, and survival in this patient population were evaluated. Overall survival was defined as date from diagnosis to death or last follow up, and progression-free survival was defined at time from cycle 1 to, progression or last follow up. Kaplan-Meier curves were fit to estimate overall and progression-free survival. Of the 134 patients evaluated, the median age at diagnosis was 65 years. Disease control rate was 62.6% (complete response: 11%, partial response: 28%, stable disease: 33%). Median overall survival from date of initial diagnosis was 15.5 months (95% confidence interval [CI] 1.06-1.5). Median progression-free survival from date of initiation of carboplatin and paclitaxel was 5.3 months (95% CI 0.34-0.5). Grade III or greater toxicity occurred in 26.1% of patients. The most common grade III toxicities were neutropenia and neuropathy, present in 14.2% and 3.7% of the total study population, respectively. In patients with metastatic or unresectable esophageal or gastric cancer, the combination of carboplatin and paclitaxel is well tolerated with comparable overall survival and progression-free survival to existing regimens in this population.

Review of current best practice and priorities for research in radiation oncology for elderly patients with cancer: the International Society of Geriatric Oncology (SIOG) task force

Radiotherapy (RT) is a key component of the management of older cancer patients. Level I evidence in older patients is limited. The International Society of Geriatric Oncology (SIOG) established a task force to make recommendations for curative RT in older patients and to identify future research priorities. Evidence-based guidelines are provided for breast, lung, endometrial, prostate, rectal, pancreatic, oesophageal, head and neck, central nervous system malignancies and lymphomas. Patient selection should include comorbidity and geriatric evaluation. Advances in radiation planning and delivery improve target coverage, reduce toxicity and widen eligibility for treatment. Shorter courses of hypofractionated whole breast RT are safe and effective. Conformal RT and involved-field techniques without elective nodal irradiation have improved outcomes in non-small-cell lung cancer (NSCLC) without increasing toxicity. Where comorbidities preclude surgery, stereotactic body radiotherapy (SBRT) is an option for early-stage NSCLC and pancreatic cancer. Modern involved-field RT for lymphoma based on pre-treatment positron emission tomography data has reduced toxicity. Significant comorbidity is a relative contraindication to aggressive treatment in low-risk prostate cancer (PC). For intermediate-risk disease, 4-6 months of hormones are combined with external beam radiotherapy (EBRT). For high-risk PC, combined modality therapy (CMT) is advised. For high-intermediate risk, endometrial cancer vaginal brachytherapy is recommended. Short-course EBRT is an alternative to CMT in older patients with rectal cancer without significant comorbidities. Endorectal RT may be an option for early disease. For primary brain tumours, shorter courses of postoperative RT following maximal debulking provide equivalent survival to longer schedules. MGMT methylation status may help select older patients for temozolomide alone. Stereotactic RT provides an alternative to whole-brain RT in patients with limited brain metastases. Intensity-modulated radiation therapy provides an excellent technique to reduce dose to the carotids in head and neck cancer and improves locoregional control in oesophageal cancer. Best practice and research priorities are summarised.

SU-E-J-187: Evaluation of the Effects of Dose on 4DCT-Calculated Lung Ventilation

PURPOSE

To investigate the effects of radiation therapy (RT) treatment dose on ventilation.

METHODS

Optical flow deformable image registration of the normal end-expiration and end-inspiration phases of 4DCT images was used to correlate the voxels between the two phases. 4DCT sets from before and after RT were used to derive ventilation for 3 SBRT lung patients. Planning dose and normalized ventilation were superimposed on the CT volume resulting in each voxel having a volume, a normalized ventilation and a dose. From these values a 3D dose-ventilation-volume surfaces was created. The surface was integrated over dose to reduce the 3D surface to a 2D histogram that is easier to interpret.

RESULTS

For lung tissue regions receiving more than 20 Gy, a decrease in ventilation was observed in the three patients. Patient A (time between scans, T=26 months) showed an increase in ventilation for regions receiving a dose smaller than 20 Gy, whereas patients B (T=3 months) and C (T=6 months) did not show any change for these regions. Mean ventilation within the 20 Gy region for patient A was 0.57 before RT and 0.51 after RT; and 0.54 before and 0.48 after RT for the 30 Gy region. Mean ventilation for the 20 Gy region for patient B was 0.49 before RT and 0.47 after RT, for the 30 Gy region mean ventilation was 0.49 Gy before and 0.45 Gy after RT. Patient C's mean ventilation for the 20 Gy region was 0.54 before RT and 0.50 after RT, for the 30 Gy region mean ventilation was 0.54 before RT and 0.49 after RT.

CONCLUSIONS

Ventilation before and after radiation therapy can be measured using 4DCT and deformable image registration techniques. In a preliminary application of this approach for three patients, changes in ventilation were observed with a weak correlation between ventilation change and dose. Partially supported by a grant from Varian Medical Systems.