Role of Adjuvant Chemotherapy in Early-Stage Combined Small Cell Lung Cancer

BACKGROUND The role of adjuvant therapy in completely resected primary tumors that have components of both non- small cell lung cancer and small cell lung cancer (combined SCLC) is poorly understood. We sought to determine the potential benefits of adjuvant chemotherapy in patients who undergo complete resection for early-stage combined SCLC. METHODS Overall survival of patients with pathologic T1-2 N0 M0 combined SCLC who underwent complete resection in the National Cancer Database from 2004 to 2017, stratified by adjuvant chemotherapy vs surgery alone, was eval-uated by multivariable Cox proportional hazards modeling and propensity score-matched analysis. Patients treated with induction therapy and those who died within 90 days of surgery were excluded from analysis. RESULTS Of 630 patients who had pT1-2 N0 M0 combined SCLC during the study period, 297 patients (47%) underwent complete R0 resection. Adjuvant chemotherapy was administered to 63% of patients (n = 188), and 37% of patients underwent surgery alone (n = 109). In unadjusted analysis, the 5-year overall survival was 61.6% (95% CI, 50.8-70.7) for patients who underwent surgery alone and 66.4% (95% CI, 58.4-73.3) for patients who underwent adjuvant chemotherapy. In multivariable and propensity score-matched analysis, there were no significant differences in overall survival between adjuvant chemotherapy and surgery alone (adjusted hazard ratio, 1.16; 95% CI, 0.73-1.84). These findings were consistent when limited to patients who underwent lobectomies or to healthier patients who have at most 1 major comorbidity. CONCLUSIONS In this national analysis, patients with pT1-2 N0 M0 combined SCLC treated with surgical resection alone have similar outcomes to those who undergo adjuvant chemotherapy.