Role Of Postoperative Radiotherapy Research Articles

Role of Postoperative Radiotherapy on High-Risk Stage pIIIA-N2 Non-Small Cell Lung Cancer Patients After Complete Resection and Adjuvant Chemotherapy: A Retrospective Cohort Study.

The aim of the study was to assess the effectiveness of postoperative radiotherapy in high-risk patients with stage pIIIA-N2 non-small cell lung cancer (NSCLC) following complete resection and adjuvant chemotherapy. Data from NSCLC patients within the Surveillance, Epidemiology, and End Results (SEER) database were analyzed. The study examined the association between lymph node ratio (LNR) and both cancer-specific survival (CSS) and overall survival (OS) using restricted cubic spline curves. Patients were categorized into high- and low-risk groups based on established LNR cut-off values, and survival outcomes were compared between those receiving postoperative radiotherapy and those who did not within the high-risk group. The study included 1,690 patients. An LNR threshold of 0.29 was identified for both CSS and OS. Patients with an LNR ≥ 0.29 demonstrated significantly worse CSS (hazard ratio (HR) = 1.56, 95% confidence interval (CI): 1.37 - 1.78; P < 0.001) and OS (HR = 1.44, 95% CI: 1.28 - 1.62; P < 0.001) compared to those with an LNR < 0.29. In the high-risk group (LNR ≥ 0.29), postoperative radiotherapy did not significantly affect CSS (HR = 0.98, 95% CI: 0.82 - 1.17; P = 0.809) or OS (HR = 0.95, 95% CI: 0.81 - 1.11; P = 0.533). LNR is a significant prognostic factor in patients with stage pIIIA-N2 NSCLC post complete resection and adjuvant chemotherapy. A higher LNR (≥ 0.29) is associated with poorer CSS and OS. However, postoperative radiotherapy does not confer survival benefits in these high-risk patients. Our findings suggest that postoperative radiotherapy should not be routinely performed in this subgroup. Further research is required to explore effective treatment strategies for these patients.

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.

The role of postoperative radiotherapy or chemoradiation in pT1-2N1M0 oral squamous cell carcinoma

BackgroundPostoperative radiotherapy (PORT) and concurrent chemoradiation (CCRT) are indicated for patients with advanced oral cancer. However, the benefits for pT1-2N1 disease without adverse pathological features are controversial. MethodsThis retrospective study using the Taiwan Cancer Registry database included patients with pT1-2N1 oral cancer from January 1, 2011, to December 31, 2017. Overall survival was analyzed in patients receiving surgery alone, PORT, or CCRT. ResultsAmong the 862 patients, the five-year overall survival rate in patients receiving surgery alone, PORT, and CCRT was 62.2%, 58.7%, and 71.1% (P = 0.03), respectively. CCRT was associated with longer survival than PORT (P = 0.008). Survival in patients with pT2 disease was significantly higher with CCRT than PORT (P = 0.001), but no difference was observed in pT1 disease. ConclusionCCRT demonstrated a favorable impact on survival outcomes in patients diagnosed with pT2N1 oral cancer when compared to PORT. However, no significant survival benefits were observed for patients with pT1 disease.

Meningeal Solitary Fibrous Tumor: A Single-Center Retrospective Cohort Study.

Meningeal solitary fibrous tumors (SFTs) are rare, malignant, mesenchymal tumors of the central nervous system. While surgical gross total resection is widely accepted as a positive prognostic factor for local control (LC), the role of postoperative radiotherapy (PORT) remains controversial. We sought to report our institutional experience with a particular focus on outcomes after PORT. In this single-center, retrospective cohort study, 20 patients with the primary diagnosis of histopathologically confirmed meningeal SFT were analyzed. Data on patient characteristics, imaging, treatment modalities, histopathology, and oncological outcomes were collected. LC and overall survival (OS) were assessed using the Kaplan-Meier estimator. The median follow-up time was 95.8 months. After surgery only, 9 out of 11 patients (81.8%) developed a local recurrence while, after surgery and PORT, 3 out of 9 patients (33.33%) showed local failure. The 5- and 10-year LC rates were 50.5% and 40.4% in the surgery-only group and 80% at both time points in the surgery with the PORT group. In the surgery-only group, 4 out of 11 patients (36.4%) died, and 4 out of 9 patients (44.4%) died in the surgery and PORT group. OS rates after 5 and 10 years were 88.9% and 66.7% in the surgery-only group and 88.9% and 76.2% in the surgery with PORT group. Our findings suggest that PORT may improve LC in patients with meningeal SFT. The low incidence of meningeal SFT impedes prospective studies and requires further international collaborative efforts to exploit retrospective datasets and molecular analysis to improve patient outcomes.

The Role of Postoperative Radiotherapy in T4 Rectal Cancer with Synchronous Distant Metastasis

Studieson the role of surgery and local treatment in M1 rectal cancer have been actively studied recently. However, there is still controversy because no significant results have been reported for local control. The purpose of this study was to analyze the local control rates of postoperative radiotherapy for tumor stage T4 in M1 rectal cancer. We investigated local recurrence after surgery for M1 rectal cancer that was operated at Seoul St. Mary's Hospital between 1995 and 2021. Locoregional recurrence rates were compared in patients who received postoperative pelvic radiotherapy and those who did not. In addition, an analytical comparison was performed only for patients with T4 rectal cancer. Statistical analysis was performed using the log rank test, and a p-value of less than 0.05 was considered significant. During the investigation period, a total of 206 patients underwent surgery for M1 rectal cancer. There were 55 patients with T4 tumor stage. Of the 55 patients, 11 patients received radiotherapy after surgery, and 44 patients received systemic treatment such as chemotherapy after surgery without radiotherapy. During a median follow-up of 22 months, locoregional recurrence occurred in 1 (RT group) and 25 (no RT group) patients, respectively. Log-rank analysis of locoregional recurrence showed a significant difference between the two groups (p- value = 0.008). Death occurred in 10 (RT group) and 38 (no RT group) patients, respectively. The 2-year locoregional recurrence free-survival rates were 45.5% and 53.0%, respectively, and there was no significant difference between the two groups in the log-rank analysis. Pelvic radiotherapy could be expected to improve locoregional recurrence in stage T4 of rectal cancer with synchronous distant metastasis. It would be warranted to prove this in a large-scale prospective study.

The role of postoperative radiotherapy (PORT) in lymphoepithelial carcinoma of the salivary gland (LECSG) and the effect of postoperative EBV DNA on prognosis

BackgroundWhether postoperative radiotherapy (PORT) could improve survival and the role of EBV DNA remains unclear for patients with lymphoepithelial carcinoma of the salivary glands (LECSG). Patients and methods360 patients were included. Independent prognostic factors were selected using a Cox proportional hazards model and incorporated into risk stratification. ResultsThe number of positive lymph nodes (PLNs) ≥ 3 and tumor size ≥ 3 cm were independent factors for PFS in patients with neck dissection (ND). Patients were divided into three groups: high-risk, size ≥ 3 cm&PLNs ≥ 3; intermediate-risk, size < 3 cm&PLNs ≥ 3 or size ≥ 3 cm&PLNs < 3; low-risk, size < 3 cm&PLNs < 3. The 5-year PFS rate of the low-, intermediate- and high-risk patients receiving non-PORT and PORT was 87.9% vs 93.5% (p = 0.12), 41.2% vs 81.1% (p < 0.001), 18.0% vs 51.1% (p = 0.034). N stage was an independent factor for PFS in patients with non-neck dissection (NND) and patients were divided into two groups: low-risk, N0; and high-risk, N1/2. The 5-year PFS rate of the low-risk, and high-risk patients receiving non-PORT and PORT was 77.9% vs 94.3% (p = 0.0019), 21.4% vs 71.3% (p = 0.015). Compared with EBV DNA = 0, the 5-year PFS rate of patients with EBV DNA > 0 was 19.9% vs 91.3% (p < 0.001). In patients with EBV DNA = 0, the 5-year PFS rate of patients with or without PORT was 95.1% vs 92.3% (p = 0.082); while in patients with EBV DNA > 0, the 5-year PFS rate was 37% vs 9.2% (p = 0.0056). ConclusionsIn patients with ND, PLNs < 3&size < 3 cm patients did not benefit from PORT. Detectable EBV DNA after surgery was a negative prognostic factor.

Postoperative Radiation Therapy Is Indicated for “Low-Risk” Pathologic Stage I Merkel Cell Carcinoma of the Head and Neck Region but Not for Other Locations

The role of postoperative radiation therapy (PORT) in early stage Merkel cell carcinoma (MCC) is controversial. We analyzed the roleof PORT in preventinglocal recurrences (LR)among patients withlow-risk,pathologicstage IMCCbased on the location of the primary tumors: head/neck (HN) versus non-HN sites. One hundred forty-seven patients with MCC were identified that had "low risk" disease (pathologic T1primary tumor, negative microscopic margins, negative pathologic node status,no immunosuppressionorprior systemic therapy).LR was defined as tumor recurrence within 2 cm of the primary surgical bed, andits frequency wasestimated with thecumulative incidencemethod. Seventy-ninepatients receivedPORT (30HN,49non-HN) with a median dose of 50 Gy (range, 8-64 Gy) and68patients were treated with surgery alone (30HN,38non-HN). Overall, PORT was associated with a decreased risk of LR (5-year rate: 0% vs 9.5%; P=.004) with6LRs observed in the surgery alone group. Although the addition of PORT significantly reduced LR rates among patients with HN MCC (0% vs. 21%; P=.034), no LRs were observed in patients with non-HN MCC managed with surgery alone. There was no significant difference inMCC-specific survival comparing HN versus non-HN groups, with or without PORT. Forlow-risk,pathologic stage IMCCoftheextremitiesand trunk, excellent local control rates were achieved with surgery, and PORT is not indicated. However, PORT was associated with a significant reduction in LRs among low-risk MCC of the HN.

The protective role of postoperative radiation therapy in low and intermediate grade major salivary gland malignancies: A study of the Canadian Head and Neck Collaborative Research Initiative.

The objective of this study was to examine the utility of postoperative radiation for low and intermediate grade cancers of the parotid and submandibular glands. The authors conducted a retrospective, Canadian-led, international, multi-institutional analysis of a patient cohort with low or intermediate grade salivary gland cancer of the parotid or submandibular gland who were treated from 2010 until 2020 with or without postoperative radiation therapy. A multivariable, marginal Cox proportional hazards regression analysis was performed to quantify the association between locoregional recurrence (LRR) and receipt of postoperative radiation therapy while accounting for patient-level factors and the clustering of patients by institution. In total, 621 patients across 14 tertiary care centers were included in the study; of these, 309 patients (49.8%) received postoperative radiation therapy. Tumor histologies included 182 (29.3%) acinic cell carcinomas, 312 (50.2%) mucoepidermoid carcinomas, and 137 (20.5%) other low or intermediate grade primary salivary gland carcinomas. Kaplan-Meier LRR-free survival at 10years was 89.0% (95% confidence interval [CI], 84.9%-93.3%). In multivariable Cox regression analysis, postoperative radiation therapy was independently associated with a lower hazard of LRR (adjusted hazard ratio, 0.53; 95% CI, 0.29-0.97). The multivariable model estimated that the marginal probability of LRR within 10years was 15.4% without radiation and 8.8% with radiation. The number needed to treat was 16 patients (95% CI, 14-18 patients). Radiation therapy had no benefit in patients who had early stage, low-grade salivary gland cancer without evidence of nodal disease and negative margins. Postoperative radiation therapy may reduce LLR in some low and intermediate grade salivary gland cancers with adverse features, but it had no benefit in patients who had early stage, low-grade salivary gland cancer with negative margins.

Individualized prediction of survival benefit from postoperative radiotherapy for patients with malignant pleural mesothelioma.

The role of postoperative radiotherapy (PORT) in malignant pleural mesothelioma (MPM) remains controversial and the eighth edition TNM staging scheme for MPM has not been fully verified. We aimed to develop an individualized prediction model for identifying optimal candidates for PORT among MPM patients who received surgery plus chemotherapy and externally validate the performance of the new TNM staging scheme. Detailed characteristics of MPM patients during 2004-2015 were retrieved from SEER registries. Propensity score matching (PSM) was conducted to reduce disparities of baseline characteristics (age, sex, histologic type, stage, and type of surgery) between the PORT group and no-PORT group. A novel nomogram was constructed based on independent prognosticators identified by multivariate Cox regression model. The discriminatory performance and degree of calibration were evaluated. We stratified patients into different risk groups according to nomogram total scores and estimated the survival benefit of PORT in different subgroups in order to identify the optimal candidates. We identified 596 MPM patients, among which 190 patients (31.9%) received PORT. PORT conferred significant survival benefit in the unmatched population, while there was no significant survival difference favoring PORT in the matched population. The C-index of the new TNM staging scheme was closed to 0.5, which represented a poor discriminatory ability. A novel nomogram was constructed based on clinicopathological factors, including age, sex, histology, and N stage. We stratified patients into three risk groups. Subgroup analyses indicated that PORT was beneficial for high-risk group (p = 0.003) rather than low-risk group (p = 0.965) and intermediate-risk group (p = 0.661). We established a novel predictive model, which could make individualized prediction of survival benefit of PORT for MPM and could compensate for weakness in TNM staging system.

Prognostic factors and role of postoperative radiotherapy in surgically resected thymomas

ObjectiveTo investigate the prognostic factors in and role of postoperative radiotherapy (PORT) for surgically resected thymomas. MethodsA total of 1540 patients with pathologically confirmed thymomas undergoing resection between 2000 and 2018 were identified retrospectively from the SEER (Surveillance, Epidemiology, and End Results) database. Tumors were restaged as local (limited to thymus), regional (invasion to mediastinal fat and other neighboring structures), or distant stage. Disease-specific survival (DSS) and overall survival (OS) were estimated by the Kaplan–Meier method and the log-rank test. Adjusted hazard ratios (HRs) with 95% CIs were calculated by Cox proportional hazards modeling. ResultsTumor stage and histology were independent predictors of both DSS (regional: HR, 3.711; 95% CI, 2.006-6.864; distant: HR, 7.920; 95% CI, 4.061-15.446; type B2/B3: HR, 1.435; 95% CI, 1.008-2.044) and OS (regional: HR, 1.461; 95% CI, 1.139-1.875; distant: HR, 2.551; 95% CI, 1.855-3.509; type B2/B3: HR, 1.409; 95% CI, 1.153-1.723). For patients with regional stage and type B2/B3 thymomas, PORT was associated with better DSS after thymectomy/thymomectomy (HR, 0.268; 95% CI, 0.099-0.727), but the association was not significant after extended thymectomy (HR, 1.514; 95% CI, 0.516-4.44). Among patients with lymph node metastases, those who received PORT (HR, 0.372; 95% CI, 0.146-0.949), chemotherapy (HR, 0.843; 95% CI, 0.303-2.346), or both (HR, 0.296, 95% CI, 0.071-1.236) had a better OS. ConclusionsThe extent of invasion and tumor histology were independent predictors of worse survival following surgical resection of thymoma. Patients with regional invasion and type B2/B3 thymoma who undergo thymectomy/thymomectomy may benefit from PORT, while patients with nodal metastases may benefit from multimodal therapy, including PORT and chemotherapy.

A case report of an ischaemic stroke, caused by a primary cardiac intimal sarcoma

BackgroundIntimal sarcomas are an extremely rare type of primary cardiac malignancy. They most commonly present with symptoms of cardiac dysfunction. We present a case of intimal sarcoma identified without any cardiac signs or symptoms. Cardiac sarcomas historically carry a very poor prognosis.PresentationA 57-year-old man presented with a sudden onset of left limb weakness and disorientation. MRI brain identified an acute ischaemic stroke in the right anterior temporal lobe. Four months later, he presented again with transient left arm weakness. The patient had a normal cardiovascular examination and ECG. All other initial investigations for cryptogenic stroke were non-contributory. The patient did not initially get an echocardiogram. When this investigation was performed, after his second presentation, a large pedunculated mass was present in his left atrium. This was resected and identified histologically as a primary intimal sarcoma of his left atrium. The patient was treated with post-operative radiotherapy but declined chemotherapy. He recovered well post-operatively but subsequently passed away 14 months after diagnosis.ConclusionsIt is possible for primary cardiac malignancies to present with only symptoms of systemic emboli. For this reason, echocardiography is a crucial investigation in cases of cryptogenic stroke. Some stroke guidelines do not definitively support routine echocardiography. Primary intimal cardiac sarcoma is a very rare condition with a poor prognosis. The literature is limited to case reports and optimal management is with surgical resection where possible. The role of post operative radiotherapy and chemotherapy is uncertain.

Multi-institutional study on the role of post-operative radiotherapy in elderly patients with endometrial cancer

ObjectiveTo investigate the prognostic factors for survival and toxicities in elderly (≥65 years) patients with endometrial cancer who underwent post-operative radiotherapy. Additionally, to compare the treatment outcomes between the older...

SUV39H1 Expression as a Guideline for Omitting Radiotherapy in Lymph Node-positive Triple-negative Breast Cancer Patients.

The role of postoperative radiotherapy (RT) combined with chemotherapy (CT) for lymph node-positive (LN+) triple-negative breast cancer (TNBC) remains controversial. SUV39H1-mediated epigenetic regulation is associated with cancer cell migration, invasion, metastasis, and treatment resistance. This study aims to identify the role of SUV39H1 in TNBCs. Overall, 498 TNBCs with SUV39H1 RNA-seq profiles were retrieved from TCGA-BRCA and analyzed; the X-tile algorithm was used to stratify the population into low, intermediate, and high SUV39H1. Furthermore, we performed an in vitro clonogenic cell survival assay using the MDA-MB-231 cell line to assess the effects of SUV39H1 on cellular responses. The results showed that SUV39H1 was significantly higher in TNBC than normal tissue and luminal subtype breast cancer. Notably, SUV39H1 is significantly expressed in the basal-like 1 (BL1) and immunomodulatory (IM) subgroups, compared to other subtypes. Compared to patients with a low or medium expression of SUV39H1, omitting RT only worsens disease-free survival (DFS) in those with high SUV39H1 expression. The experimental results showed SUV39H1 was suppressed by si-SUV39H1, and SUV39H1 knockdown in MDA-MB-231-IV2-1 cells enhanced the cellular toxicity of doxorubicin and paclitaxel. Targeting SUV39H1 may provide a potential guiding indication of omitting RT to avoid over-treatment and chemosensitivity for TNBC.

Effect of postoperative radiotherapy on survival in patients with completely resected and pathologically confirmed stage N2 non-small-cell lung cancer: a systematic review and meta-analysis.

The role of postoperative radiotherapy (PORT) for patients with completely resected stage N2 non-small-cell lung cancer (NSCLC) has been controversial. This study aimed to investigate the efficacy of PORT and prognosis in these patients. An updated meta-analysis was conducted in this study to investigate the efficacy of PORT and prognosis in patients with completely resected and pathologically confirmed stage N2 NSCLC. This study is a systematic review and meta-analysis. Databases were searched up to 2 March 2022. All trials on patients with completely resected and pathologically confirmed stage N2 NSCLC undergoing PORT were screened, and data indicators in the PORT and non-PORT groups were extracted, respectively. The effect of PORT on overall survival (OS), disease-free survival (DFS), local recurrence-free survival (LRFS), and distant metastasis-free survival (DMFS) was estimated. Subgroup and sensitivity analyses were performed. In all, 20 studies involving 6340 patients were finally included. The PORT significantly increased OS [hazard ratio (HR) = 0.77, 95% CI: 0.71-0.84, p < 0.001), LRFS (HR = 0.63, 95% CI: 0.52-0.76, p < 0.001), and DFS (HR = 0.72, 95% CI: 0.63-0.82, p < 0.001) while it showed no significant difference in improving DMFS (HR = 0.86, 95% CI: 0.71-1.05, p = 0.14). Our results suggest that in the postoperative treatment of patients with completely resected and pathologically confirmed stage N2 NSCLC, the addition of PORT provides better local recurrence control and survival benefit, but no benefit for distant metastases. The PORT may be incorporated into the postoperative treatment options for some patients with high-risk factors. However, it needs to be validated by more prospective studies in the future. CRD42022314095.

Uncertain resection of highest mediastinal lymph node positive among pN2 non-small cell lung cancer patients: survival analysis of postoperative radiotherapy and driver gene mutations.

The role of postoperative radiotherapy (PORT) in uncertain resection of pN2 non-small cell lung cancer (NSCLC) with highest mediastinal lymph node positive has not been determined. We aim to evaluate the effect of PORT and driver gene mutation status (DGMS) on survival in such patients. 140 selected patients were grouped according to whether they received PORT and their DGMS. Locoregional recurrence-free survival (LRFS), distant metastasis-free survival (DMFS), disease-free survival (DFS), and overall survival (OS) of each group were evaluated by Kaplan-Meier analyses. COX regression was used to evaluate the effects of various factors on DFS and OS. Of 140 patients, thirty-four patients (24.3%) received PORT, and forty (28.6%) had positive driver gene mutation status (DGp). PORT significantly prolonged LRFS (p = 0.002), DFS (p = 0.019) and OS (p = 0.02), but not DMFS (p = 0.062). By subgroup analysis, in patients with negative driver gene mutation status (DGn), those receiving PORT had notably longer LRFS (p = 0.022) and DFS (p = 0.033), but not DMFS (p = 0.060) or OS (p = 0.215), compared to those not receiving PORT. Cox analysis showed that the number of positive lymph nodes (PLNs) and administration of PORT were independent prognostic factors of DFS, and pathology, PLNs, and DGMS may be prognostic factors of OS (all p < 0.05). Postoperative radiotherapy may improve locoregional recurrence-free and disease-free survival in patients with pN2 NSCLC with positive highest mediastinal lymph nodes, while driver gene mutation status impacted OS significantly. Only patients with positive driver gene mutations experienced significant overall survival benefits from postoperative radiotherapy.

Role of postoperative radiotherapy in resected adenoid cystic carcinoma of the head and neck

PurposeAlthough postoperative radiotherapy (PORT) is demonstrably effective in local control of head and neck adenoid cystic carcinoma (HNACC), its application is controversial and the subset of patients who would benefit most from PORT is unknown. Herein, we analyzed the data of HNACC patients to clarify the role of PORT.MethodsWe retrospectively reviewed 187 patients with nonmetastatic HNACC who underwent surgical resection between 2005 and 2019. The study endpoints were locoregional failure-free survival (LRFFS), progression-free survival (PFS), and overall survival (OS). Subgroup analysis and recursive partitioning analysis (RPA) were performed to identify patients most likely to benefit from PORT.ResultsWith a median follow-up of 84.7 months, the 5-year LRFFS, PFS, and OS were 70.0%, 52.6%, and 86.4%, respectively. Survival was significantly shorter in patients who experienced local failure than in those who did not (5-year OS: 88.1% vs. 80.5%, P = 0.001). The local failure rate was significantly lower in patients who underwent PORT (16.9% vs. 31.0%, P = 0.021), despite the high frequency of adverse factors. Especially, significant decreases in local failure and similar OS rates could be obtained after PORT among patients with positive margins, T2-4 stage disease, and minor salivary gland tumors. The RPA model for PFS categorized patients into four groups according to three prognostic factors (T-stage, location, and sex). The RPA model for LRFFS and OS suggested three groups based on two factors (T-stage, margin for LRFFS; T-stage, grade 3 for OS).ConclusionPORT could prevent dismal survival, while significantly reducing local failures in high-risk HNACC patients.

Adjuvante Mediastinalbestrahlung bei nichtkleinzelligem Lungenkarzinom (pN2)

BackgroundPatients with non-small-cell lung cancer (NSCLC) have a high risk for developing mediastinal relapse. Although adjuvant chemotherapy is the standard of care in locally advanced disease, the role of postoperative radiotherapy (PORT) has not been clearly defined. Over the past 50 years, several prospective, randomized trials and meta-analyses have been conducted addressing this question. While patients without mediastinal lymph node involvement do not benefit from PORT, meta-analyses have suggested that patients with pN2 disease could benefit from PORT. Recently two prospective phase III randomized trials (LungART and PORT-C) were conducted testing PORT vs. no PORT in patients with stage IIIA/pN2 disease. There was no significant difference in disease-free (DFS) or overall survival between the two groups but there was a significant difference in the risk of mediastinal relapse in both studies. In the PORT C study, there was a statistically significant improvement in DFS and local recurrence-free survival at 3 years in the “per protocol” analysis. Selected patients with risk factors, such as extracapsular extension, R1 resection, or with a high mediastinal burden might benefit from PORT.ConclusionPORT does not lead to survival benefit in unselected patients with stage IIIA/pN2 NSCLC after complete resection without extracapsular lymph node extension. Selected patients with risk factors, such as extracapsular extension, R1 resection or with a high mediastinal burden, could benefit from PORT by significantly reducing the risk of mediastinal relapse.

Machine Learning to Refine Selection Criteria of Post-Operative Radiotherapy for Resectable Stage III-N2 Non-Small Cell Lung Cancer

<h3>Purpose/Objective(s)</h3> The role of post-operative radiotherapy (PORT) for completely resected N2 non-small cell lung cancer (NSCLC) is controversial, given the recently published LungART and PORT-C trials. We sought to utilize machine learning to identify a subset of patients who may still benefit from PORT based on the extent of nodal involvement. <h3>Materials/Methods</h3> Patients with completely resected N2 NSCLC were identified in the National Cancer Database diagnosed between 2004 and 2017. The query was subsequently limited to patients with pN2 disease, known pathologic T stage, and no evidence of distant metastasis. Patients were excluded if they had unknown follow-up, did not undergo surgery (lobectomy, bilobectomy, or pneumonectomy), did not undergo lymph node dissection, had positive margins, had unknown number of positive lymph nodes or total lymph nodes examined, or received neoadjuvant radiation. We trained a machine-learning based model of overall survival (OS). SHapley Additive exPlanation values (SHAP) were used to identify prognostic and predictive thresholds for the number of positive lymph nodes (LNs) involved and lymph node ratio (LNR). Multivariable (MVA) Cox proportional-hazards regression was used for confirmatory analysis. <h3>Results</h3> A total of 16,789 patients with completely resected N2 NSCLC were identified. Of the patients that met inclusion criteria, 6181 (36.8%) received PORT. When radiation treatment technique could be determined, about half received 3D conformal radiation therapy (18.7% of all patients) and about half received IMRT (19.9% of all patients). Median follow-up for the entire cohort was 32.0 months (0-183.1 months). Median OS of the whole population was 41.7 months (95%CI: 40.7-43.1). For patients who received PORT, median OS was 47.6 months (95%CI: 45.2-49.7). For patients who did not receive PORT, median OS was 38.6 months (95%CI: 37.1-39.9). Using SHAP values, we identified thresholds of 3+ positive LNs and a LNR of 0.34+. On MVA, PORT was not significantly associated with OS (HR: 0.96; 95%CI: 0.92-1.01); (p=0.111). However, a subset analysis of patients with 3+ positive LNs revealed that PORT improved OS (HR: 0.91; 95%CI: 0.86-0.97; p=0.002). Patients with 3+ positive LNs had a 5-year OS of 38% (95%CI: 36-40%) with PORT compared to 31% (95%CI: 29-32%) without PORT. Patients with 1-2 positive LNs had a 5-year OS of 49% (95%CI: 47-51%) with PORT compared to 44% (95%CI: 43-46%) without PORT. On a separate subset analysis, in patients with a LNR of 0.34+, PORT improved OS (HR: 0.90; 95%CI: 0.85-0.96; p=0.001). Patient with positive LNR of 0.34+ had a 5-year OS of 38% (95%CI: 36-40%) with PORT compared to 29% (95%CI: 28-31%) without PORT. Patients with a positive LNR of 0.00-0.33 had a 5-year OS of 47% (95%CI: 45-49%) with PORT compared to 43% (95%CI: 42-44%) without PORT. <h3>Conclusion</h3> This study suggests that patients with 3+ positive LNs or a LNR of 0.34+ may present a subpopulation of patients who could benefit from PORT. These findings warrant further investigation in a future prospective study.

EP05.01-027 Uncertain Resection of pN2 NSCLC Patients-survival Analysis of Postoperative Radiotherapy and Driver Gene Mutations

The role of postoperative radiotherapy (PORT) in uncertain resection of pN2 non-small cell lung cancer (NSCLC) with highest mediastinal lymph node positive has not been determined. We aim to evaluate the effect of PORT and driver gene mutation status (DGMS) on survival in such patients.

The role of postoperative radiotherapy in patients with uterine sarcomas: A PSM-IPTW analysis based on SEER database.

ObjectiveThe optimal adjuvant therapy for uterine sarcomas remains poorly determined due to its rarity and histological diversity. The purpose of the study is to explore and characterize the association between utilization of radiotherapy and survival outcome in patients with surgically resected uterine sarcomas.MethodsWe collected data regarding uterine sarcomas which were confirmed after total hysterectomy between 2010 and 2018 period from the latest version of the Surveillance, Epidemiology, and End Results (SEER) database. Initially, 1-, 3- and 5-year survival rate were calculated to predict potential risk factors and possible role of adjuvant chemotherapy and radiotherapy. Propensity score matching (PSM) and inverse probability treatment weighting (IPTW) technique were employed to balance confounding factors in the utilization of additional therapy. Multivariate and exploratory subgroup analyses were respectively conducted to evaluate the impact of adjuvant therapy on overall survival (OS) and cause-specific survival (CSS).ResultsA total of 2897 patients were enrolled in the analysis. Survival benefit at 1-, 3-and 5-year after initial treatment was observed in the group of radiotherapy given, however, poorer prognosis in the group of chemotherapy administration. Accordingly, chemotherapy was enrolled as a confounding factor when stratifying and matching patients by receipt of radiotherapy. Prior to and after PSM-IPTW adjustment, radiotherapy both demonstrated beneficial effect on OS and CSS based on multivariate analysis. Further subgroup analysis indicated radiotherapy improved OS and CSS among a subset of patients in stage II-IV, particularly with uterine leiomyosarcoma, tumor grade IV, bigger tumor size than 100 mm and even with chemotherapy administration.ConclusionsAdjuvant radiotherapy in uterine sarcomas after hysterectomy might be underutilized, and proper use of adjuvant radiotherapy combined with chemotherapy after surgery in advanced-stage and high-risk patients might improve survival.