97P - Pattern of first-site failure and salvage treatment in patients with inoperable stage III non-small cell lung cancer after chemoradiotherapy

Abstract

Background: The standard of care treatment for inoperable stage III NSCLC is concurrent chemoradiotherapy (CRT) followed by consolidation with durvalumab. Loco-regional and distant recurrences remain common. Herein, we examine pattern of first-site failure and salvage treatment. Methods: We analysed the medical charts of 99 patients treated with CRT. Scans from date of first-site failure were fused with the delivered treatment plans. Recurrences were identified as in-field recurrence (IFR), out-of-field recurrence (OFR) [outside 50Gy isodose line] and distant metastases (DM). Using the Kaplan-Meier method with log-rank test for univariate analysis, the effect of salvage surgery (S), radiotherapy (sRT), chemotherapy (sCT) and immunotherapy (sIO) on overall survival (OS) was evaluated. Results: With a median follow-up of 17.2 months, the mOS for all patients was 20.8 months. 26 patients (26%) with IFR had a mOS of 19.3 months. In patients who survived at least 12 months from initial diagnosis (74%), IFR was a significant negative prognosticator (mOS 19.3 vs 40.0 months; p < 0.001). 25 (25%) patients developed OFR with no significant impact on survival (27.1 vs 20.8 months, p = 0.313). 3 (12%) patients with OFR underwent salvage surgery (p = 0.057) and were still alive at the time of this analysis. 5 (20%) patients underwent sRT with a mOS of 71.2 vs 19.1 months (p = 0.014). 13 (52%) patients with OFR received sCT; mOS 26.4 vs 32.7 mo. (p = 0.644;) and 4(16%) pts received sIO (mOS: 64.6 vs 26.4 months; p = 0.222). Distant and brain relapse were detected in 42 (42%) and 16 (16%) patients; mOS 19.1 vs. 22.9 months (p = 0.819) and 19.1 vs 20.8 mo. (p = 0.635), respectively. 15 (94%) patients with brain relapse received cranial radiotherapy: 7 (47%) whole brain irradiation and 8 (53%) stereotactic radiosurgery (mOS 15.3 vs. 37.8 mo.; p = 0.064). Conclusions: IFR was a significant negative predictor of OS in patients, who survived >1 year after initial diagnosis. Patients with OFR benefit most from salvage operation and/or radiotherapy. Furthermore, we observed survival benefit in patients who received SRS vs. WBRT for brain relapse. Legal entity responsible for the study: The authors. Funding: Has not received any funding. Disclosure: All authors have declared no conflicts of interest.