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e20555 Background: The indications for post-operative radiation therapy (PORT) in locally advanced non-small cell lung cancer (NSCLC) remain undefined and a major concern is the perceived risk of increased mortality from cardiopulmonary causes. The purpose of this study was to quantify the rate of cardiopulmonary death in patients with resected NSCLC receiving PORT using a large national database. Methods: Using the Surveillance, Epidemiology, and End Results (SEER) database for lung cancer, patients with Stage IIIA or Stage IIIB NSCLC according to the 6th AJCC edition treated with surgery followed by PORT, who also received chemotherapy were identified. Cause of death was categorized as due to lung cancer, other cancer, cardiac, pulmonary, or other and reported as a percentage of total deaths at one and 2 years. Kaplan-Meier survival analysis was done to compare overall survival between Stage IIIA and IIIB patients. Results: From 2004 to 2015, 4387 patients with stage IIIA and IIIB meeting the eligibility criteria were identified. The median age at diagnosis was 65 years old, most patients were male (53%), Caucasian (83%), had adenocarcinoma (54.8%), stage IIIA disease (69%), and N2 disease (78%). The median overall survival for Stage IIIA and IIIB patients was 39 months and 27 months respectively (p < 0.001). Among the 2586 patients that died during the study period, the most common COD was lung cancer (81.3%). Cardiac and pulmonary COD occurred in 86 patients (3.3% of deaths) and 84 patients (3.2% of deaths) respectively, whereas 158 patients (6.1%) died from other cancers and 154 (5.9%) from other causes. There were 77 deaths from cardiopulmonary cause at 2 years (1.7% of patients and 2.9% of deaths). Cardiopulmonary COD was more common in patients with stage IIIB compared to IIIA disease (4.9% vs 3.3% of deaths, p < 0.001). Lung cancer was the most common COD both at 1 and 2 years (85%) whereas cardiopulmonary was the COD in 5.2% of patients at 1 year and 5.1% at 2 years. Conclusions: This analysis showed a low cardiopulmonary mortality from PORT in the first 2 years. The role for adjuvant radiotherapy remains undefined and treatment decisions for patients with resected stage III NSCLC should be guided by co-morbidities and the competing risk for death from lung cancer.

8548 Background: NRG-RTOG 0617 (R0617) found that non-personalized dose escalation of radiotherapy (RT) with concurrent chemotherapy was deleterious. NRG-RTOG 1106/ACRIN 6697 (R1106) studied adaptive chemoradiotherapy, using tumor and patient individualized RT dose intensification simultaneously with field reduction, based upon mid-treatment FDG-PET. Methods: The control arms of both studies used 60 Gy (+ weekly carboplatin/paclitaxel). The investigational arm of R0617 used 74 Gy in 37 fractions, with no field/dose adaptation, while R1106 used mid-treatment FDG-PET (after ̃40 Gy) to design an individualized dose adaptive RT plan with daily-fraction size 2.2 to 3.8 Gy (up to 80.4 Gy/30 fractions), based upon a model of isotoxic lung risk. Nearly all (93%) patients had IMRT. No patients had consolidation immunotherapy. The primary endpoint for R1106 was local-regional-progression freedom (LRPF) assessed by central review. Other endpoints reported here were survival, toxicity, and institution-defined local/regional control. Results: From 2012-2017, 127 patients were enrolled to R1106 (43 in the standard and 84 in the adaptive arms), with a median follow-up of 3.6 years. The median actual RT dose in the adaptive arm was 71 Gy (Q1-Q3 68-76 Gy). The 2-year LRPF was 59.5% versus 54.6% (p=0.66) for standard versus adaptive RT; the 3-year survival rates were 49.1% versus 47.5% (p=0.80). An exploratory analysis of 2-year in-field local primary tumor control and local-regional tumor control (institution-assessed) were 58.5% and 55.6% for standard RT, and 75.6% and 66.3% for adaptive RT, respectively. As shown in the table, there were no significant differences in cardiac or esophageal adverse events between the two arms; the adaptive RT arm had more Grade 3+ respiratory events (23.8% versus 14.3%). Conclusions: NRG-RTOG1106 did not meet its primary endpoint of demonstrating improved LRPF. Unlike R0617, there was no suggestion of a detrimental effect of adaptive dose-intensified RT on survival and cardiac events. Studies to refine personalized RT, especially in the immunotherapy era, should be considered. Outcome comparison between R0617 and R1106. Clinical trial information: NCT01507428. [Table: see text]

Purpose Although intensity-modulated radiation therapy (IMRT) is increasingly used to treat locally advanced non–small-cell lung cancer (NSCLC), IMRT and three-dimensional conformal external beam radiation therapy (3D-CRT) have not been compared prospectively. This study compares 3D-CRT and IMRT outcomes for locally advanced NSCLC in a large prospective clinical trial. Patients and Methods A secondary analysis was performed to compare IMRT with 3D-CRT in NRG Oncology clinical trial RTOG 0617, in which patients received concurrent chemotherapy of carboplatin and paclitaxel with or without cetuximab, and 60- versus 74-Gy radiation doses. Comparisons included 2-year overall survival (OS), progression-free survival, local failure, distant metastasis, and selected Common Terminology Criteria for Adverse Events (version 3) ≥ grade 3 toxicities. Results The median follow-up was 21.3 months. Of 482 patients, 53% were treated with 3D-CRT and 47% with IMRT. The IMRT group had larger planning treatment volumes (median, 427 v 486 mL; P = .005); a larger planning treatment volume/volume of lung ratio (median, 0.13 v 0.15; P = .013); and more stage IIIB disease (30.3% v 38.6%, P = .056). Two-year OS, progression-free survival, local failure, and distant metastasis–free survival were not different between IMRT and 3D-CRT. IMRT was associated with less ≥ grade 3 pneumonitis (7.9% v 3.5%, P = .039) and a reduced risk in adjusted analyses (odds ratio, 0.41; 95% CI, 0.171 to 0.986; P = .046). IMRT also produced lower heart doses ( P < .05), and the volume of heart receiving 40 Gy (V40) was significantly associated with OS on adjusted analysis ( P < .05). The lung V5 was not associated with any ≥ grade 3 toxicity, whereas the lung V20 was associated with increased ≥ grade 3 pneumonitis risk on multivariable analysis ( P = .026). Conclusion IMRT was associated with lower rates of severe pneumonitis and cardiac doses in NRG Oncology clinical trial RTOG 0617, which supports routine use of IMRT for locally advanced NSCLC.