Use Of Postoperative Radiotherapy Research Articles

Supramarginal resection of skull base chordomas: proof of concept and preliminary outcomes.

The mainstay of treatment for skull base chordoma (SBC) is maximal safe resection followed by radiotherapy. However, even after gross-total resection (GTR), the recurrence rate is high due to microscopic disease in the resection margins. Therefore, supramarginal resection (SMR) could be beneficial, as has been shown for sacral chordoma. The paradigm of postoperative radiation therapy for every patient has also begun to change, as molecular profiling has shown variability in the risk of recurrence. The aim of this study was to present the concept of SMR applied to SBC, along with an individualized decision for postoperative radiation therapy. This is a retrospective analysis of all SBCs operated on by the senior author between 2018 and 2023. SMR was defined as negative histological margins of bone and/or dura mater, along with evidence of bone resection beyond the tumor margins in the craniocaudal and lateral planes on postoperative imaging. Tumors were classified into 3 molecular recurrence risk groups (group A, low risk; group B, intermediate risk; and group C, high risk). Postoperative radiation therapy was indicated in group C tumors, in group B chordomas without SMR, or in cases of patient preference. Twenty-two cases of SBC fulfilled the inclusion criteria. SMR was achieved in 12 (55%) cases, with a mean (range) amount of bone resection beyond the tumor margins of 10 (2-20) mm (+40%) in the craniocaudal axis and 6 (1-15) mm (+31%) in the lateral plane. GTR and near-total resection were each achieved in 5 (23%) cases. Three (19%) tumors were classified as group A, 12 (75%) as group B, and 1 (6%) as group C. Although nonsignificant due to the small sample size, the trends showed that patients in the SMR group had smaller tumor volumes (13.9 vs 19.6 cm3, p = 0.35), fewer previous treatments (33% vs 60% of patients, p = 0.39), and less use of postoperative radiotherapy (25% vs 60%, p = 0.19) compared to patients in the non-SMR group. There were no significant differences in postoperative CSF leak (0% vs 10%, p = 0.45), persistent cranial nerve palsy (8% vs 20%, p = 0.57), and tumor recurrence (8% vs 10%, p = 0.99; mean follow-up 15 months) rates between the SMR and non-SMR groups. In select cases, SMR of SBC appears to be feasible and safe. Larger cohorts and longer follow-up evaluations are necessary to explore the benefit of SMR and individualized postoperative radiation therapy on progression-free survival.

Prognostic Factors and Outcomes in World Health Organization Grade 1 and Grade 2 Intracranial Meningiomas—5-Year Institutional Experience

Meningiomas are the most frequent primary intracranial tumour. While histological grade and grade of excision are established predictors of recurrence, nuances such as the role of radical excision of dural attachment and postoperative radiotherapy in intermediate-risk groups remain unanswered. This report presented data from 451 WHO Grade 1 and 248 WHO Grade 2 intracranial meningiomas operated between 2010 and 2015, analysing their clinical and radiological features and surgical details. Outcomes were assessed among 352 WHO Grade 1 and 208 WHO Grade 2 meningiomas, studying the effect of extent of resection and use of radiotherapy. Kaplan Meier analysis was used to determine differences in survival by extent of resection and use of postoperative radiotherapy in the treatment of WHO Grade 1 and 2 meningiomas. The mean age of the cohort was 46.3 years, with a female predominance. On univariate analysis, gender, WHO grade, and Simpson grade were significant predictors of recurrence. On multivariate analysis, WHO grade and Simpsons grade remained significant predictors of recurrence. Recurrence was significantly associated with poor performance status and mortality. Postoperative radiation significantly improved progression-free survival among Grade 2 meningioma that underwent gross total resection (GTR), but not among WHO Grade 1 and 2 meningioma after subtotal resection (STR). WHO Grade and Simpson grade are independent predictors of recurrence among meningiomas. Irrespective of Grade, gross total resection must be effected when possible, and postoperative radiotherapy may be recommended in Grade 2 meningioma.

The Role of Postoperative Radiotherapy in the Management of Dermatofibrosarcoma Protuberans: A Multidisciplinary Systematic Review.

Background: Dermatofibrosarcoma protuberans (DFSP) is a superficial soft tissue sarcoma, and surgical excision is the first-line treatment. The aim of this systematic review is to provide an update about the current indications and clinical results regarding the use of postoperative radiotherapy in DSFP, considering both adjuvant and salvage setting. Methods: We conducted a systematic literature review using the main scientific database, including Cochrane library, Scopus, and PubMed, for any relevant article about the topic, and we considered all available papers without any time restriction. Results: Twenty-two papers, published between 1989 and 2023, were retrieved and considered eligible for inclusion in this review. Regarding the fractionation schedules, most authors reported using standard fractionation (2 Gy/die) with a wide total dose ranging from 50 to 70 Gy. The local control after postoperative radiotherapy was excellent (75-100%), with a median follow-up time of 69 months. Conclusions: After the primary surgical management of DFSP, postoperative radiotherapy may either be considered as adjuvant treatment (presence of risk factors, i.e., close margins, recurrent tumours, aggressive histological subtypes) or as salvage treatment (positive margins) and should be assessed within the frame of multidisciplinary evaluation.

Do Patients Treated With an Unplanned Resection for Small Superficial Soft Tissue Sarcomas Have Worse Long-term Survival Than Those Initially Treated With an Oncologic Resection?

Histologic grade, size, and depth are well-known prognostic factors in soft tissue sarcomas (STS). Small (< 5 cm) and superficial STS generally have an excellent prognosis when treated with appropriate surgery. However, they are often misdiagnosed and mistreated. We reported that in midterm follow-up (5 to 7 years), patients with unplanned resections of tumors with positive margins who immediately underwent a reoperation with margin-widening re-resection and postoperative radiotherapy had survival comparable to that of patients who were initially treated correctly. In that article, we included STS larger than 5 cm, deep STS, and individuals with local recurrence. However, we wanted to evaluate the impact of unplanned resection on the survival of patients who had STS with the best prognosis, small and superficial STS, with two groups that were as homogeneous as possible. Do patients with small and superficial STS who underwent an unplanned resection have worse prognosis in the long term than those who were initially treated correctly? We exclusively evaluated patients with small (< 5 cm) and superficial (to the deep fascia) STS. We systematically excluded deep STS. Among this subset, we identified 93 patients with superficial STS. We excluded patients with local relapse, metastatic disease, superficial STS of the head or neck, those with insufficient clinical or dosimetric information, and patients with follow-up of less than 2 years. Furthermore, our focus on investigating the most benign and homogeneous STS prompted us to exclude patients with superficial tumors greater than or equal to 5 cm. This selection was driven by the presumed better prognosis associated with smaller tumors, inevitably leading to a smaller pool of patients for direct comparison with patients who had unplanned resections. The initial expectation was to observe similar survival outcomes between cohorts. Between 1990 and 2019, a total of 17 patients underwent surgical treatment at our private, medium-size center. Of those, 29% (5 patients) were lost to follow-up before 2 years without meeting a study endpoint (relapse, metastasis or revision, reoperation, or death), leaving a total of 71% (12 patients) of the original group who had either follow-up of at least 2 years or who met a study endpoint before that minimum surveillance duration. They were treated with surgery alone. During that same period, another 51 patients were referred to us after undergoing an unplanned resection of a lesion that subsequently was determined to be a soft tissue malignancy. Of those, 18% (9 patients) were lost to follow-up before 2 years without meeting a study endpoint, leaving 82% (42 patients) of the original group who had either follow-up of at least 2 years or who met a study endpoint before that minimum surveillance duration. They were treated with re-excision and postoperative radiotherapy. Patients with unplanned resections had an older mean age (51± 5 versus 44 ± 7 years; p = 0.1) and a higher proportion of female patients (58% versus 38%; p = 0.07), but the groups did not differ in terms of largest diameter, histologic type, or tumor location. However, patients with planned resections had a higher proportion of high-grade STS (75% versus 55%; p = 0.07). No metastases were present in either group at diagnosis. We performed a univariate analysis of the groups. We could not perform a multivariate analysis because of the small sample. We compared the groups in terms of local recurrence and all-cause mortality using the Kaplan-Meier survivorship estimator. According to the Kaplan-Meier survivorship estimator, survivorship free from local recurrence at a mean of 20 years of follow-up was better in the planned resection group than in the unplanned resection group (92% [95% CI 63% to 100%] versus 69% [95% CI 54% to 81%]; p = 0.04). Furthermore, overall survivorship at 5 years was higher in the planned resection group than in the unplanned resection group (100% [95% CI 72% to 100%] versus 70% [95% CI 54% to 81%]; p = 0.04). Similarly, the planned resection group exhibited superior survivorship at 20 years of follow-up (100% [95% CI 72% to 100%] versus 62% [95% CI 47% to 75%]; p = 0.01). Metastatic disease was absent in the planned resection group, while it occurred in 12 patients in the unplanned resection group (28% [95% CI 17% to 44%]). Unplanned resection for patients with small and superficial STS was associated with a decrease in overall survival in the long term, despite the use of postoperative radiotherapy. An unplanned resection may be an important prognostic factor. Nevertheless, larger and prospective studies are needed to validate our findings. Although small and superficial lumps are usually benign, nonsarcoma surgeons should be aware that some masses may be malignant, and if in doubt, MR imaging, a biopsy before excision, or consultation with or referral to a sarcoma center should be considered before removing the mass. Level III, therapeutic study.

What Are the Recurrence Rates, Complications, and Functional Outcomes After Multiportal Arthroscopic Synovectomy for Patients With Knee Diffuse-type Tenosynovial Giant-cell Tumors?

What Are the Recurrence Rates, Complications, and Functional Outcomes After Multiportal Arthroscopic Synovectomy for Patients With Knee Diffuse-type Tenosynovial Giant-cell Tumors?

Decreasing utilization for postoperative radiation therapy in locoregionally advanced medullary thyroid cancer.

Use of postoperative radiation therapy (PORT) in locoregionally advanced medullary thyroid cancer (MTC) remains controversial. The objective was to evaluate the effect of PORT on locoregional control (LRC) and overall survival (OS). Retrospective cohort study of 346 MTC patients separated into PORT and no-PORT cohorts. Relative indications for PORT, as well as changes in patterns of treatment, were recorded. 49/346 (14%) received PORT. PORT was associated with worse OS; adjusted HR = 2.0 (95%CI 1.3-3.3). PORT was not associated with improved LRC, even when adjusting for advanced stage (Stage III p = 0.892; Stage IV p = 0.101). PORT and targeted therapy were not associated with improved OS compared to targeted therapy alone; adjusted HR = 1.2 (95%CI 0.3-4.1). Use of PORT in MTC has decreased and its indications have become more selective, coinciding with the advent of effective targeted therapies. Overall, PORT was not associated with improved LRC or OS.

Patterns of Care in Craniopharyngioma: Clinical Outcomes After Surgery and Radiation Therapy in a Real-World Setting

Craniopharyngioma (CP) is a benign neuroepithelial tumor generally treated with maximal safe resection and radiation therapy (RT) in incompletely resected CP or in recurrent tumors to achieve long-term control. We analyzed the clinical outcomes of patients with CPs treated with a multimodality approach. A retrospective clinical audit of histologically proven CPs registered between 2008 and 2019 at a specialized neuro-oncology center in India was performed. Time-to-event outcomes (overall survival [OS] and progression-free survival [PFS]) were analyzed. One hundred and twenty-two patients with CP were analyzed. The median age of the population was 14 years (interquartile range [IQR], 8-26) with a significant male preponderance. Gross total resection was achieved in only 25% of patients. At a median follow-up of 57.1 months (IQR, 27.8-87.8), 5-year estimates of PFS and OS were 52% (95% confidence interval, 46%-63.4%) and 85.8% (95% confidence interval, 78.6%-93%), respectively. Recurrence or progression was observed in 48 of 122 patients (39.3%) at a median time of 84.4 months (IQR, 24.7-174.8). On multivariate analysis, the absence of residual disease (P= 0.004), near-total resection (P= 0.035), and use of up-front adjuvant RT (P < 0.001) significantly improved the 5-year PFS, whereas the absence of extracavernous extension (P= 0.058) and any use of postoperative RT (P= 0.026) significantly improved the 5-year OS. This study represents one of the largest single-institutional series of CPs, showing improved PFS with up-front adjuvant RT in most cases of CP. Deferring adjuvant RT should be considered only in patients with no evidence of residual disease (as shown on dedicated sellar imaging) after primary surgery.

SP32. Predicting The “Crunch”: Capsular Contraction Prediction in Two-stage Breast Reconstruction Using Neural Network

PURPOSE: Two-stage breast reconstruction is a common technique used to restore pre-operative appearance in patients undergoing mastectomy. However, capsular contracture may develop and lead to significant discomfort. The objective of this study is to build a machine learning model that can evaluate the risk of capsular contracture after two-stage breast reconstruction. METHODS: 209 women (406 samples) were included in the cohort. Patient characteristics that remained statistically significant predictors of capsular contracture were included as input data in the machine learning model. Supervised learning models were evaluated using k-fold cross validation (k=3). A neural network model was also evaluated with a 0.8/0.1/0.1 train/validate/test split on the dataset. RESULTS: Among the subjects, 144/406 (35.47%) developed capsular contracture. Older age (OR 1.0), smaller nipple-inframammary fold distance (OR 0.90), slower tissue expansion rate/longer time delay (OR 0.998), and the use of post-operative radiation (OR 3.46) increased odds of capsular contracture (p<0.05). Neural network achieved the best performance metrics among the models tested, with test accuracy of 0.82 and ROC AUC 0.79. CONCLUSION: To our knowledge, this is the first study that uses neural network model to predict the development of capsular contraction after two-stage implant-based breast reconstruction. The application of machine learning will allow for better counseling of patients prior to breast reconstruction. High risk patients may be guided to autologous reconstruction or advised of the potential for additional surgeries. It may also provide better instruction on who should use acellular dermal matrix or other adjuvant techniques at the time of initial reconstruction.

ASTRO Radiation Therapy Summary of the ASCO Guideline on Management of Stage III Non-Small Cell Lung Cancer

To develop a radiation therapy summary of recommendations on the management of locally advanced non-small cell lung cancer (NSCLC) based on the Management of Stage III Non-Small Cell Lung Cancer: American Society of Clinical Oncology Guideline, which was endorsed by the American Society for Radiation Oncology (ASTRO). The American Society of Clinical Oncology, ASTRO, and the American College of Chest Physicians convened a multidisciplinary panel to develop a guideline based on a systematic review of the literature and a formal consensus process, that has been separately published. A new panel consisting of radiation oncologists from the original guideline as well as additional ASTRO members was formed to provide further guidance to the radiation oncology community. A total of 127 articles met the eligibility criteria to answer 5 clinical questions. This summary focuses on the 3 radiation therapy questions (neoadjuvant, adjuvant, and unresectable settings). Radiation-specific recommendations are summarized with additional relevant commentary on specific questions regarding the management of preoperative radiation, postoperative radiation, and combined chemoradiation. Patients with stage III NSCLC who are planned for surgical resection, should receive either neoadjuvant chemotherapy or chemoradiation. The addition of neoadjuvant treatment is particularly important in patients planned for surgery in the N2 or superior sulcus settings. Postoperatively, patients who did not receive neoadjuvant chemotherapy should be offered adjuvant chemotherapy. The use of postoperative radiation for completely resected N2 disease is not routinely recommended. Unresectable patients with stage III NSCLC should ideally be managed with combined concurrent chemoradiation using a platinum-based doublet with a standard radiation dose of 60 Gy followed by consolidation durvalumab in patients without progression after initial therapy. Patients who cannot tolerate a concurrent chemoradiation approach can be managed either by sequential chemotherapy followed by radiation or by dose-escalated or hypofractionated radiation alone.

Prediction nomogram development and validation for postoperative radiotherapy in the management of oral squamous cell carcinoma

Predictive nomograms are useful tools to guide clinicians in estimating disease course. Oral squamous cell carcinoma (OSCC) patients would benefit from an interactive prediction calculator that defines their levels of survival-risk specific to their tumors to guide the use of postoperative radiotherapy (PORT). Patients with OSCC surgically treated with curative intent at four Head and Neck Cancer Centres were recruited retrospectively for development and validation of nomograms. Predictor variables include PORT, age, T and N classification, surgical margins, perineural invasion, and lymphovascular invasion. Outcomes were disease-free, disease-specific, and overall survivals over 5 years. 1296 patients with OSCC were in training cohort for nomogram analysis. Algorithms were developed to show relative benefit of PORT in survivals for higher-risk patients. External validation on 1212 patients found the nomogram to be robust with favorable discrimination and calibration. The proposed calculator can assist clinicians and patients in the decision-making process for PORT.

Combined modality treatment of operable breast cancer using intraoperative radiotherapy

Objective of the study: To review worldwide literature data on the efficacy of combined modality treatment including intraoperative radiation therapy (IORT) in patients with operable breast cancer (BC). Material and Мethods. Of 110 publications (2000–2021) available from Scopus, Pubmed, Elibrary and other databases, using the key “breast cancer”, “local recurrence”, “intraoperative radiotherapy” and “radiation technique”, 45 were included in the literature review. Results. Radiotherapy is of paramount importance in the organpreserving treatment of breast cancer, as numerous randomised studies have shown that the use of postoperative radiotherapy dramatically reduces the number of locoregional recurrences. The use of IORT as an effective method of relapse prevention compared to standard postoperative adjuvant radiotherapy is an important trend in radiation oncology.Conclusion. The use of IORT in combination treatment modality for operable breast cancer should be differentiated and based on clinical and morphological prognostic factors. Different molecular subtypes of breast cancer are characterized by significant differences in pathogenesis and response to therapy. Further studies on the effectiveness of IORT are required to identify a group of patients with absolute indications for the use of IORT.

Nomograms for Metastasis-Free and Overall Survival for Pathologically Node Positive Prostate Cancer Patients Treated With or Without Radiation Therapy Plus Short-Term ADT.

We aimed to develop nomograms to predict the risk reduction for metastasis and death in pathologically node-positive (pN +) prostate cancer patients treated with or without radiation therapy (RT). From a prospectively gathered institutional database, we identified patients with pN+M0 prostate cancer after surgery. We evaluated several regression models of known or suspected clinical-pathologic covariates and selected the model with the highest Harrell's concordance-index (c-index) and clinical utility to prognosticate metastasis for inclusion in a nomogram. Covariates in the final, competing-risk adjusted, metastasis model included PSA nadir after surgery, pathologic T-stage, margin status, Gleason score (GS), number of positive lymph nodes, and use of postoperative radiotherapy combined with androgen deprivation therapy (RT+ADT). The overall survival model also included Charlson comorbidity score and age. 336 pN+men with a mean age of 64.9 years and a median follow-up of 4.1 years who had a radical prostatectomy were included in the analysis. 83 men were recommended RT+ADT, of whom 4% refused the ADT and received RT alone. C-index was 0.85 and 0.71 for the MFS and OS models, respectively. On multivariable analysis (MVA) adjusted for competing risks, RT+ADT significantly improved MFS (HR=0.70 P=< .01) with number of nodes positive, GS 8-10, PSA nadir > 1 ng/mL, and pT3b prognostic for metastasis. MVA for OS demonstrates RT+ADT improves survival (HR=0.40, P=.02), with GS8-10 and PSA nadir > 1.0 prognostic for death. We developed predictive nomograms for patients with pN+ prostate cancer following radical prostatectomy. These models can discretely quantify an individual's risk of metastasis or death with and without post-prostatectomy radiotherapy.

Postoperative radiotherapy for meningiomas – a decision-making analysis

BackgroundThe management of meningiomas is challenging, and the role of postoperative radiotherapy is not standardized.MethodsRadiation oncology experts in Swiss centres were asked to participate in this decision-making analysis on the use of postoperative radiotherapy (RT) for meningiomas. Experts from ten Swiss centres agreed to participate and provided their treatment algorithms. Their input was converted into decision trees based on the objective consensus methodology. The decision trees were used as a basis to identify consensus and discrepancies in clinical routine.ResultsSeveral criteria used for decision-making in postoperative RT in meningiomas were identified: histological grading, resection status, recurrence, location of the tumour, zugzwang (therapeutic need to treat and/or severity of symptoms), size, and cell division rate. Postoperative RT is recommended by all experts for WHO grade III tumours as well as for incompletely resected WHO grade II tumours. While most centres do not recommend adjuvant irradiation for WHO grade I meningiomas, some offer this treatment in recurrent situations or routinely for symptomatic tumours in critical locations. The recommendations for postoperative RT for recurrent or incompletely resected WHO grade I and II meningiomas were surprisingly heterogeneous.ConclusionsDue to limited evidence on the utility of postoperative RT for meningiomas, treatment strategies vary considerably among clinical experts depending on the clinical setting, even in a small country like Switzerland. Clear majorities were identified for postoperative RT in WHO grade III meningiomas and against RT for hemispheric grade I meningiomas outside critical locations. The limited data and variations in clinical recommendations are in contrast with the high prevalence of meningiomas, especially in elderly individuals.

Outcome of cutaneous squamous cell carcinoma with microscopic residual disease after surgery and usefulness of postoperative radiotherapy: a retrospective cohort study.

Microscopic residual disease (MRD) after surgery can be a challenging situation in cutaneous squamous cell carcinoma (CSCC) and there is a lack of evidence concerning its management. To evaluate the prognosis of CSCC with MRD and the usefulness of postoperative radiotherapy (PORT) in CSCC with MRD. Retrospective cohort study of CSCC with MRD through a 10-year period (2010-2019) (n = 244). Disease-free survival and event-free survival were assessed using R (v.3.4.1), considering competing risks. Evaluated outcomes were local recurrence (LR), nodal metastases (NMs), and disease-specific death (DSD). Median age was 88y (IQR: 10.5). A total of 145 (59.43%) were men and 69 (28.28%) were immunosuppressed. Median tumour diameter and thickness were 19 and 6.4 mm (IQR 11 and 5.5 mm). Patients treated by re-excision had a relapse rate of 4.3% compared with 11.30% and 29.71% in those who received PORT and observation (P = 0.045). The use of PORT was associated with a lower risk of LR compared with observation (HR = 0.206 [0.049-0.859], P = 0.030), but not with a lower risk of NMs or DSDs. In the multivariable models, PORT was again associated with a lower risk of LR than observation (HR = 0.167 [0.039-0.708], P = 0.014), but not with lower risk of metastasis and death. We always should try to obtain clear margins after surgery. PORT improves local control in CSCC with MRD, but when administered to the tumour bed, it does not reduce the risk of NM and DSD.

A Comparison of Long-Term Treatment Outcomes Between Giant and Nongiant Craniopharyngiomas

There is limited literature on outcomes after surgical treatment of giant craniopharyngiomas in adult and pediatric patients. A retrospective review of 159 patients undergoing surgery for craniopharyngiomas at a single institution was performed. Patients with giant craniopharyngiomas (maximum dimension ≥4.5 cm) were compared with nongiant tumors in terms of various clinical and radiological parameters and long-term surgical outcomes. Extent of resection was determined by postoperative magnetic resonance imaging. Factors associated with post-treatment obesity were also analyzed. Giant craniopharyngiomas (n= 66) were characterized by higher rates of childhood presentation, visual impairment, neurological deficits, multicompartmental involvement, and hydrocephalus as compared with nongiant tumors (n= 139). Giant tumors also were less likely to undergo transsphenoidal resection and were associated with a higher rate of postoperative neurological morbidity. There were no significant differences between the 2 groups in terms of extent of resection, use of postoperative radiation therapy, and long-term endocrinological outcomes. Overall recurrence rates over a mean follow-up period of 4.1 years were similar between giant and nongiant tumors; however, recurrences after presumed gross total resection/near total resection were significantly higher in the former subgroup versus the latter (39.4% vs. 18.4%; P= 0.044). Risk factors for post-treatment obesity in giant craniopharyngiomas included adult age (P= 0.001), preoperative obesity (P= 0.003), and hypothalamic involvement (P= 0.012). Gross total resection/near total resection of giant craniopharyngiomas can be achieved at rates comparable to nongiant tumors. However, there remains a greater risk of postoperative neurological morbidity. Radiation therapy mitigates the risk of recurrence on long-term follow-up.

Postoperative radiotherapy for completely resected thymoma: Differing roles in masaoka stage II and stage III disease

The efficacy of radiotherapy for treating thymomas is unclear. The goal of this study was to analyze overall survival (OS) and disease-free survival (DFS) among thymoma patients to determine the impact of postoperative radiotherapy (PORT) on thymoma outcomes. Recorded cases of thymoma at Xinqiao Hospital were retrospectively analyzed from 1991 to 2019. Data on stage II and III thymomas were extracted from medical records. This study evaluated OS and DFS and compared outcomes between surgery and surgery-plus-radiation groups. The Kaplan-Meier method and Cox regression analysis were used to compare DFS and OS for these groups. Of the 205 patients included in the current study, 142 (69.3%) presented with stage II disease and 63 (30.7%) presented with stage III disease. The median follow-up was 84.3 months. PORT did not statistically significantly improve OS (P=0.613) and DFS (P=0.445) in stage II thymoma patients (compared with surgery alone). However, our subgroup analysis showed a statistically significant difference in DFS in patients with stage III thymoma (P=0.044). Although the routine use of postoperative radiotherapy in patients with thymoma does not appear warranted, patients with stage III thymoma may benefit from adjuvant radiation. These findings, if confirmed, will provide valuable information to guide medical decision-making for thymoma treatment.

Abstract P3-19-15: Prognostic impact of radiation therapy in mucinous carcinoma of the breast

Abstract Purpose/Objectives Mucinous carcinoma (MC) of the breast is an uncommon variant of breast cancer which has a favorable prognosis. Current guidelines for ER/PR-positive, HER2-negative pure-MC state that endocrine therapy (ET) is only required for tumors ≥3cm and node-positive patients while chemotherapy (CTX) is not required but can be considered for node positive-patients. While radiation therapy (RT) currently remains a part of breast-conserving therapy (BCT) for this histology, the prognostic impact of RT in pure MC remains unclear. Materials/Methods The National Cancer Database (NCDB) was queried (2004-2017) for patients with non-metastatic, histologically confirmed MC who received breast-conserving surgery. Kaplan-Meier analysis was used to evaluate overall survival (OS). Univariate (UVA) and multivariate (MVA) analyses were conducted using Cox proportional hazard models to determine which clinical and treatment factors were prognostic for overall survival. Results A total of 24,837 patients with median age 70 (IQR 61-78) were included in this study. A total of 66% of carcinomas were grade 1 and 34% were grade 2. A total of 79% were pT1, 20% were pT2, and 1% were pT3-4. A total of 96% were pN0 and 4% were pN1-3. A total of 99% were ER+, 92% were PR+, and 96% were HER2-. A total of 61% received RT, 70% received ET, and 8% received CTX. The 10-year OS was 73% for those who received RT and 41% for those who did not. On UVA, RT (HR 0.31, p&amp;lt; 0.0001; CI 0.29-0.33), ET (HR 0.52, p&amp;lt; 0.0001; CI 0.49-0.55), CTX (HR 0.40, p&amp;lt; 0.0001; CI 0.35-0.46), and black race (HR 0.87, p= 0.006; CI 0.79- 0.96) were positive prognostic factors for OS while older age (HR 1.10, p&amp;lt; 0.0001; CI 1.09-1.10), CDCC comorbidity score (HR 1.93, p&amp;lt; 0.0001; CI 1.81- 2.06), and tumor size (HR 1.01, p&amp;lt; 0.0001; CI 1.01-1.02) were negative prognostic factors. On MVA, RT (HR 0.64, p&amp;lt; 0.0001; CI 0.59-0.69) and ET (HR 0.85, p&amp;lt; 0.0001; CI 0.78- 0.91) remained positive prognostic factors while older age (HR 1.08, p&amp;lt; 0.0001; CI 1.08-1.09), CDCC comorbidity score (HR 1.61, p&amp;lt; 0.0001; CI 1.50- 1.73), and tumor size (HR 1.02, p&amp;lt; 0.0001; CI 1.01- 1.02) remained negative prognostic factors; chemotherapy (HR 1.19, p= 0.039; CI 1.01- 1.39) became a negative prognostic factor and black race (HR 0.99, p= 0.92; CI 0.89- 1.12) was no longer prognostic. Conclusion This is the largest study to date on mucinous carcinoma of the breast and the role of RT after breast-conserving surgery. Use of postoperative RT after lumpectomy is associated with improved OS in patients with breast MC, suggesting that post-lumpectomy RT should remain standard of care. Citation Format: Neil Chevli, Kaidi Wang, Waqar Haque, Mary R. Schwartz, Julie Nangia, Jennifer Sasaki, Andrew M. Farach, Sandra S. Hatch, E. Brian Butler, Bin S. Teh. Prognostic impact of radiation therapy in mucinous carcinoma of the breast [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P3-19-15.

Rural-urban differences in secular trends of locoregional treatment for ductal carcinoma in situ: A patterns of care analysis.

PrecisOmission of PORT following BCS remains high among rural patients despite evidence that PORT leads to a significant reduction in the risk of local recurrence. Further research is needed to examine the impact of rural residence on treatment choices and develop methods to ensure equitable care among all breast cancer patients.BackgroundDespite national guidelines, debate exists among clinicians regarding the optimal approach to treatment for patients diagnosed with ductal carcinoma in situ (DCIS). While regional variation in practice patterns has been well documented, population‐based information on rural–urban treatment differences is lacking.MethodsData from the SEER Patterns of Care studies were used to identify women diagnosed with histologically confirmed DCIS who underwent cancer‐directed surgery in the years 1991, 1995, 2000, 2005, 2010, and 2015. Adjusted odds ratios (aORs) and 95% confidence intervals (CIs) were estimated using weighted multivariable logistic regression to evaluate cancer‐directed surgery and use of post‐operative radiation therapy (PORT).ResultsOf the 3337 patients who met inclusion criteria, 27% underwent mastectomy, 26% underwent breast‐conserving surgery (BCS) without PORT, and 47% underwent BCS with PORT. After adjustment for other covariates, there was no difference in the likelihood of receiving mastectomy between rural and urban patients (aOR = 0.65; 95% CI 0.37–1.14). However, rural residents were more likely than urban residents to have mastectomy during 1991/1995 (aOR = 1.78; 95% CI 1.09–2.91; p interaction = 0.022). Across all diagnosis years, patients residing in rural areas were less likely to receive PORT following BCS compared to urban patients (aOR = 0.35; 95% CI 0.18–0.67).ConclusionsOmission of PORT following BCS remains high among rural patients despite evidence that PORT leads to a significant reduction in the risk of local recurrence. Further research is needed to examine the impact of rural residence on treatment choices and develop methods to ensure equitable care among all breast cancer patients.

Association of the Oncology Care Model With Value-Based Changes in Use of Radiation Therapy

Radiation utilization for breast cancer and metastatic bone disease varies in modality, fractionation, and cost, despite evidence demonstrating equal effectiveness and consensus recommendations such as Choosing Wisely that advocate for higher value care. We assessed whether the Oncology Care Model (OCM), an alternative payment model for practices providing chemotherapy to patients with cancer, affected the overall use and value of radiation therapy in terms of Choosing Wisely recommendations. We used Centers for Medicare & Medicaid Services administrative data to identify beneficiaries enrolled in traditional fee-for-service Medicare who initiated chemotherapy episodes at OCM and propensity-matched comparison practices. Difference-in-difference (DID) analyses evaluated the effect of OCM on overall use of postoperative radiation for breast cancer, use of intensity modulated radiation therapy and hypofractionation for breast cancer, and fractionation patterns for treatment of metastatic bone disease from breast or prostate cancer. We performed additional analyses stratified by the presence or absence of a radiation oncologist in the practice. Among 27,859 postoperative breast cancer episodes, OCM had no effect on overall use of radiation therapy after breast surgery (DID percentage point difference = 0.4%; 90% confidence interval [CI], -1.7%, 2.4%) or on use of intensity modulated radiation therapy in this setting (DID=-0.6; 90% CI, -3.1, 2.0). Among 19,366 metastatic bone disease episodes, OCM had no effect on fractionation patterns for palliation of bone metastases (DID for ≤10 fractions=-1.1%; 90% CI, -2.6%, 0.4% and DID for single fraction=-0.2%; 90% CI, -1.9%, 1.6%). Results were similar for practices with and without a radiation oncologist. We did not evaluate the effect of OCM on hypofractionated radiation after breast-conserving surgery owing to evidence of differential baseline trends. OCM had no effect on use of radiation therapy after breast-conserving surgery for breast cancer or on fractionation patterns for metastatic bone disease. Future payment models directly focused on radiation oncology providers may be better poised to improve the value of radiation oncology care.

Postoperative Radiation Therapy in Oral Cavity Verrucous Carcinoma.

We investigate the clinicopathologic and treatment factors associated with the use of postoperative radiation therapy (PORT) and its effect on overall survival (OS) for patients with oral cavity verrucous carcinoma (VC). Retrospective cohort study. A retrospective cohort study of the National Cancer Database (NCDB) from 2006 to 2015 was performed. Multivariable logistic regression was used to identify independent predictive factors associated with the use of PORT. Cox Regression survival and propensity score analyses were used to evaluate the effect of PORT on mortality. A total of 356 adult patients with primary oral cavity VC who underwent definitive surgical resection were identified. A total of 10.7% of patients underwent definitive surgical resection followed by PORT. Variables associated with PORT included distance to the hospital per 10 miles (adjusted odds ratio [aOR], 0.81 [95% confidence interval (CI), 0.70-0.95]) and stage III-IV disease (aOR, 12.13 and 23.92, respectively). Multivariable Cox regression survival analysis indicated no evidence of survival benefit in patients undergoing PORT compared to surgery alone (adjusted hazard ratio 1.50 [0.74-3.05], P=.23). Propensity score analysis also showed no OS benefit with the use of PORT (P=.41). Variables associated with the use of PORT on multivariable analysis included closer distance to hospital and stage III-IV disease. No clear survival benefit with PORT was identified on either multivariable survival analysis or propensity score analysis. These results suggest that surgery alone with negative margins may be the optimal treatment for patients with oral cavity VC. 4 Laryngoscope, 132:1953-1961, 2022.