Effect of thoracic radiotherapy on mortality in limited small cell lung cancer. A meta-analysis of 13 randomized trials among 2,140 patients.

This meta-analysis was designed to evaluate the hypothesis that thoracic radiotherapy contributes to a moderate increase in overall survival in limited small-cell lung cancer. We collected individual data on all patients enrolled before December 1988 in randomized trials comparing chemotherapy alone with chemotherapy combined with thoracic radiotherapy. The study included 13 trials and 2140 patients with limited disease. A total of 433 patient with extensive disease were excluded. Overall, 1862 of 2103 patients who could be evaluated died; the median follow-up period for the surviving patients was 43 months. The relative risk of death in the combined therapy group as compared with the chemotherapy group was 0.86 (95 percent confidence interval, 0.78 to 0.94; P = 0.001), corresponding to a 14 percent reduction in the mortality rate. The benefit in terms of overall survival at three years (+/- SD) was 5.4 +/- 1.4 percent. Indirect comparison of early with late radiotherapy and of sequential with non-sequential radiotherapy did not reveal any optimal time for treatment. There was a trend toward a larger reduction in mortality among younger patients. In conclusion, thoracic radiotherapy moderately improves overall survival in patients with limited small-cell lung cancer who are treated with combination chemotherapy.