Thoracic Radiotherapy for Extensive Stage Small-Cell Lung Cancer: A Meta-Analysis

Abstract

Background: Thoracic radiotherapy (TRT) has been evaluated as a means of improving overall survival and progression-free survival in patients with extensive stage small-cell lung cancer (ES-SCLC).

Methods: A systematic review of Medline and Embase (inception to January 2015) was undertaken to identify studies of extensive stage SCLC patients receiving platinum-based chemotherapy and randomized to receive TRT versus no TRT. Studies were screened by title (n = 2343) and then abstract (n = 72), with subsequent full-text review (n = 16). Effect estimates (hazard ratios [HR] and confidence intervals) were abstracted, with a random-effects model created to estimate treatment effects. Cochrane's Q and I(2) statistics were used to assess study heterogeneity.

Results: Two randomized studies were identified, including a total of 604 patients (302 TRT; 302 non-TRT). All patients received prophylactic cranial irradiation. The weighted median age was 62 years, and 56% were male. TRT was delivered as 30 Gy/10 fractions (n = 247) or 54 Gy twice daily/36 fractions (n = 55). Overall, the delivery of TRT was associated with improved overall survival (HR, 0.81; 95% confidence interval, 0.69-0.96; P = .014) and progression-free survival (HR, 0.74; 95% confidence interval, 0.64-0.87, P < .001). For both end points, the studies were not found to be heterogeneous (P = .439 and P = .638 respectively, I(2) = 0). Bronchopulmonary toxicity (grade 3 or higher) was similar in both groups (≤ 2%). Esophageal toxicity (grade 3 or higher) was 6.6% in the TRT arm and 0% in the non-TRT arm (P < .001).

Conclusion: This systematic review with meta-analysis of 2 randomized trials indicates that TRT improves overall survival and progression-free survival in patients with extensive stage SCLC, with a small incremental risk of esophageal toxicity.

Keywords: Extensive stage; Prophylactic cranial irradiation; Small-cell lung cancer; Survival; Thoracic radiotherapy.