P49.03 Chemoradiation with Cisplatin-Etoposide versus Carboplatin-Etoposide in Limited-Stage Small Cell Lung Cancer

Abstract

There are limited data on the comparison between etoposide plus cisplatin or carboplatin in patients with limited-stage small-cell lung cancer (SCLC). Although the guidelines and published randomized trials have included only cisplatin-based chemotherapy, the COCIS (Carboplatin- or Cisplatin-Based Treatment for SCLC) meta-analysis showed no significant differences in efficacy based on platinum drug used for either limited or extensive-stage SCLC (J Clin Oncol 2012; 30: 1692-8). We conducted a retrospective study to compare the outcomes in patients with stage III SCLC treated with thoracic radiation therapy with etoposide and either cisplatin or carboplatin. Patients diagnosed with limited-stage SCLC at Washington University between January of 1997 and May of 2019 were retrospectively screened for this study. Those with stage III, who were treated with radiation therapy and chemotherapy, including etoposide plus either cisplatin or carboplatin, were included in this analysis. The Kaplan-Meier method and multivariate Cox Proportional Hazard models were used to estimate progression-free survival (PFS) and overall survival (OS). Fischer exact tests were used to test group differences for categorical variables. Among the 244 patients evaluated, 150 (61.4%) met the eligibility criteria. 69 patients (28.3%) were excluded due to stage I, II or unavailable, 17 (7.0%) due to lack of radiation therapy, and 8 (3.3%) due to the use of other chemotherapy regimens. Among the 150 patients, 68 were treated with cisplatin and 82 with carboplatin. The median age was 58 years in the cisplatin group and 67 years in the carboplatin group. While most patients were treated with concurrent chemoradiation, more patients received sequential radiation in the carboplatin group when compared to the cisplatin one (18.3% vs. 2.9%, P=0.004). There were no significant differences between the two groups regarding gender, race, or smoking status. At a median follow-up of 19 months, there was no statistical difference in PFS or OS between both groups. The median PFS was 13 months in the cisplatin group and 9 months in the carboplatin group (P=0.33). The median OS was 33 months in the cisplatin group and 26 months in the carboplatin group (P=0.1). On multivariate Cox regression analysis, chemotherapy type was not significantly associated with PFS or OS. However, increasing age at diagnosis and sequential radiation were both independently associated with increased mortality (HR:1.03 [1.00-1.05], P=0.02, and 1.97 [1.03-3.78], P=0.04, respectively). Our findings suggest that among patients with stage III SCLC treated with chemoradiotherapy, there are no significant differences in outcomes based on the platinum drug used. Although there are no ongoing randomized studies directly comparing the platinum drugs, some allow carboplatin, and their results may further clarify its role in the management of limited-stage SCLC.