Does thoracic irradiation improve survival and local control in limited-stage small-cell carcinoma of the lung? A meta-analysis.

PURPOSE: Our main purpose was to determine whether the addition of thoracic radiation therapy to systemic chemotherapy improves 2-year survival, improves local (intrathoracic) tumor control, and affects treatment-related mortality in patients with limited-stage small-cell carcinoma of the lung. DESIGN: Eleven randomized trials addressing this issue were identified using a computerized literature search (Medline and Cancerline) and by polling senior investigators in the field. A meta-analysis was then performed and the results of the trials were analyzed in two ways, the odds ratio (OR) (Peto) method and the risk difference method (Dersimonian and Laird). RESULTS: The overall OR for benefit of thoracic radiation on 2-year survival (ie, the odds of surviving 2 years among patients allocated to radiation compared with the odds of surviving 2 years among patients allocated to control) is 1.53 (95% confidence interval CI, 1.30 to 1.76; chi 2 = 12.76; P less than .001). The risk difference method showed that radiation therapy improved 2-year survival by 5.4% (95% CI, 1.1% to 9.7%). Local control results were available for only nine studies, the OR for treatment benefit is 3.02 (95% CI, 2.80 to 3.24; chi 2 = 101.48; P less than .0001), and intrathoracic tumor control was improved by 25.3% (95% CI, 16.5% to 34.1%). The OR for excess treatment-related deaths in the thoracic radiation-treated patients was 2.54 (95% CI, 1.90 to 3.18; chi 2 = 8.24; P less than .01). The risk difference for treatment-related deaths was 1.2% (95% CI, -0.6% to 3.0%). CONCLUSIONS: This meta-analysis shows a small but significant improvement in survival and a major improvement in tumor control in the thorax in patients receiving thoracic radiation therapy. However, this is achieved at the cost of a small increase in treatment-related mortality.