Indications for Adjuvant Mediastinal Radiotherapy in Surgically Resected Small Cell Lung Cancer

Background Adjuvant mediastinal radiotherapy (AMR) is used after surgical resection for patients with small cell lung cancer (SCLC), but data guiding its use are scant. We sought to examine whether AMR was associated with an improvement in survival for resected SCLC patients and to define subpopulations who should be selected for AMR. Methods Patients undergoing lobectomy, pneumonectomy, and sublobar resection for SCLC were identified in the National Cancer Database (2004 to 2013). Kaplan-Meier survival curves and Cox proportional hazards were used to evaluate associations between AMR and survival. Hazard ratios were adjusted for patient comorbidity, demographics, tumor characteristics, such as stage, grade, histology, and margin status, and receipt of adjuvant chemotherapy. Results We identified 3,101 patients. Those receiving AMR were younger, more likely to have greater pathologic T and N stage, to undergo sublobar resection, and to have a positive margin. Kaplan-Meier curves showed better median survival for patients with pN1 or pN2 disease who received AMR. After adjustment, Cox models showed AMR was associated with a lower risk of death for pN1 (hazard ratio, 0.79; 95% confidence interval, 0.63 to 1.00; p = 0.05) and pN2 (hazard ratio, 0.60; 95% confidence interval, 0.48 to 0.75; p < 0.0001). In the overall cohort, AMR was not associated with better survival in node-negative patients. AMR was, however, associated with improved survival for patients receiving sublobar resection (hazard ratio, 0.72; 95% confidence interval, 0.57 to 0.90; p = 0.004). Conclusions AMR is associated with longer survival for node-positive patients after resection for SCLC, especially those with pN2. AMR may also be associated with longer survival in patients undergoing sublobar resections.