Retrospective cohort study assessing clinical outcomes of patients with extensive-stage small cell lung cancer treated with and without consolidative thoracic radiotherapy at the Princess Margaret Cancer Centre.

Abstract

Most patients with small cell lung cancer present with extensive-stage (ES-SCLC) disease. An international randomised trial demonstrated a survival benefit in patients treated with consolidative thoracic radiotherapy (cTRT). We report our institutional experience with this regimen. A retrospective review was conducted on patients with ES-SCLC who were candidates for cTRT at our institution between 2013 and 2022. The patients included in our study had biopsy-proven ES-SCLC, received ≥4 cycles of chemotherapy and achieved complete response, partial response or stable disease as per Response Evaluation Criteria in Solid Tumors V.1.1. Overall survival, progression-free survival (PFS) and recurrence patterns were compared between patients who received cTRT and those who did not. For patients who received cTRT, treatment tolerability was assessed. We identified 123 patients with ES-SCLC who received ≥4 cycles of chemotherapy and were candidates for cTRT. Of those, 49 patients received cTRT, and 74 patients did not. From the end of chemotherapy, the control group had a median OS of 0.6 years with a 1- and 2-year OS of 23.5% and 11.0%. Within the cTRT group, the median OS was 0.9 years with a 1- and 2-year OS of 46.7% and 26.3%. Within the control group, the median PFS was 0.2 years compared with 0.4 years within the cTRT group. Intrathoracic failures in the cTRT group were lower compared with the control group (16.3% vs 29.7%). cTRT was well tolerated with no grade 3+ toxicities. The improved clinical outcomes of cTRT for patients with ES-SCLC were comparable to the reported the Chest Radiotherapy Extensive-Stage Small Cell Lung Cancer Trial (CREST) outcome, with a low rate of side effects in our study cohort.