The Role of Adjuvant Therapy in Advanced Thymic Carcinoma: A National Cancer Database Analysis

Background: There is area of controversy and variability in the recommendation for the role of adjuvant therapy after R0 resection of a Masaoka stage IIB and III thymic carcinoma. This study investigated the role of adjuvant therapy in patients who had complete surgical resection for thymic carcinoma. Methods: Patients with stage IIB and III thymic carcinoma who underwent curative resection were queried and categorized according to Masaoka-Koga stage groups from the National Cancer Database. Patients were grouped by treatment status (surgery only or surgery followed by adjuvant therapy). Kaplan-Meier estimates of overall survival and univariate and multivariate Cox proportional hazards regression analyses were performed. Results: From 2004 to 2013, 632 surgical patients with stage IIB and III thymic carcinoma were selected for analysis. In stage IIB patients, the adjuvant therapy group had improved survival compared with the surgery only group (P = .01), although no survival difference was observed in patients who had R0 resection between the 2 groups (P = .59). In multivariate analysis, age (P < .001) and grade III and IV (P = .02) negatively impacted survival; the adjuvant therapy improved survival (P < .02). For stage III cancer, the adjuvant therapy group had improved survival compared with the OS group regardless of margin status. In multivariate analysis, tumor size exceeding 70 mm (P = .02) and positive margin (P < .01) negatively affected survival; adjuvant therapy improved survival (P < .01). Conclusions: Adjuvant therapy showed no benefit in patients with stage IIB cancer who had R0 resection. Use of adjuvant therapy should be strongly considered for stage IIB cancer patients with positive margins and all stage III thymic cancer patients.