Objective To explore the effect of sequential thoracic radiotherapy on extensive-disease small cell lung cancer (ED-SCLC) compared with consolidative radiotherapy.

Methods We collected 102 patients with ED-SCLC who received thoracic radiotherapy from January 2010 to June 2013. The progression free survival (PFS) and overall survival (OS) of two radiotherapy arms (sequential vs. consolidative radiotherapy) were analyzed by Kaplan-Meier curve method.

Results The median PFS and 1-year PFS rates were 11.0 month, and 39.6% in sequential thoracic radiotherapy group, 9.4 month and 4.6% in consolidative radiotherapy group (P=0.000). The median OS, 1-year and 2-year OS rates were 15.0m, 77.7% and 4.6% in sequential group, 14.2m, 82.4% and 2.4% in consolidative group (P=0.58). Univariate analysis showed that performance status (PS) score (=0), cycles of chemotherapy ( > 3) and sequential thoracic radiotherapy were significantly associated with better PFS (P=0.005) and multivariate analysis indicated that cycles of chemotherapy ( > 3) and sequential radiotherapy were independent favorable prognostic factors. Further, subgroup analysis showed that whether chemotherapy cycles > 3 or≤3, the PFS of patients who received sequential thoracic radiotherapy was longer.

Conclusion Sequential thoracic radiotherapy could improved the PFS of some highly selective patients with ED-SCLC. Cycles of chemotherapy ( > 3) and sequential thoracic radiotherapy are two independent prognostic factors.