315P PREDIRAD-NSCLC: Predictors of radiation pneumonitis in non-small cell lung cancer

Background: Stage III NSCLC represents a heterogeneous disease.Platinum-based chemotherapy remains the corner stone.Accurate staging is essential; however, any substantial discordance between clinical and pathological staging may affect treatment allocation and outcome.This study uses real-world data from the Baden-Wrttemberg Cancer Registry (BWCR) to characterize staging accuracy in operated patients and outcomes of major curative-intent treatments in stage III NSCLC.Methods: We identified 10,700 adults with non-metastatic NSCLC diagnosed 2017-2024 who received treatment in curative intent.Two cohorts were analyzed: 1) Primary surgery with pathological stage III (pIII, n = 1010), 2) Definitive chemoradiotherapy (RCT) durvalumab (Durva) with clinical stage III (cIII, n = 604).Only treatments according to the German S3 guidelines were included.Endpoints were overall survival (OS) and time to progression. Results:Staging accuracy was evaluated in all patients with initial surgery (n=3981).Clinical-pathological staging discordance here was substantial, with agreement only in 42.0%.Upstaging was more common (31.8%) than down-staging (26.2%).In group I, adjuvant platinum therapy (n=537) improved OS versus surgery alone (n=473; HR 0.52, 95%CI 0.4-0.7).Cisplatin (n=340) and carboplatin (n=197) showed comparable OS (HR 1.0).Median time to progression was 452 days for both platinum groups versus 329 days for surgery alone (p = 0.034).In group II, Durva maintenance conferred the highest benefit (RCT+Durva vs. RCT; HR 0.55, 95%CI 0.4-0.7).Here cisplatin was more effective in non-squamous tumors, while in squamous tumors both platinums performed comparable.Median time to progression was longest for cisplatin-RCT + Durva (339 days), followed by cisplatin-RCT (283), carboplatin-RCT + Durva (280) and carboplatin-RCT (218).Conclusions: Real-world evidence from BWCR interestingly reveals considerable staging discrepancy in non-metastatic NSCLC.Adjuvant platinum therapy confers benefit to pIII-patients irrespective of platinum regimen, while in cIII-disease, Durva maintenance and histology-specific platinum selection significantly influence outcomes.