Timing of chest radiotherapy in patients with limited stage small cell lung cancer: a systematic review and meta-analysis of randomised controlled trials

BACKGROUND: We undertook a systematic review and literature-based meta-analysis to determine whether the timing of chest radiotherapy may influence the survival of patients with limited stage small cell lung cancer (LS-SCLC). OBJECTIVES: To establish the most effective way of combining chest radiotherapy with chemotherapy for patients with limited-stage small cell lung cancer in order to improve long-term survival. MATERIALS: Eligible studies were identified according to the Cochrane Collaboration Guidelines and were randomised controlled clinical trials comparing different timing of chest radiotherapy in patients with LS-SCLC. Early chest irradiation was defined as beginning within 30 days after the start of chemotherapy. RESULTS: Seven randomised trials were eligible. The overall survival at 2 years or at 5 years was not significantly different between early or late chest radiotherapy. When only trials were considered that used platinum chemotherapy concurrent with chest radiotherapy, significantly higher 2 and 5-year survival rates were observed when chest radiotherapy (RT) was started within 30 days after the start of chemotherapy (2-year survival: HR: 0.73, 95% CI 0.57-0.94, p=0.01; 5-year survival: HR: 0.65, 95% CI 0.45-0.93, p=0.02). This was even more pronounced when the overall treatment time of chest radiotherapy was less than 30 days. In studies that did not show a survival advantage by early chest radiation, a lower dose-intensity of chemotherapy in the early vs. late arm was observed. CONCLUSIONS: When platinum-based chemotherapy concurrently with chest RT is used, the 2- and 5-year survival rates of patients with LS-SCLC may be in favour of early chest radiotherapy, with a significant difference if the overall treatment time of chest radiation is less than 30 days.