Systematic Review Evaluating the Timing of Thoracic Radiation Therapy in Combined Modality Therapy for Limited-Stage Small-Cell Lung Cancer

Abstract

Purpose: We employed meta-analytic techniques to evaluate early (E) versus late (L) timing of thoracic radiation therapy (RT) in limited-stage small-cell lung cancer (LS-SCLC). In addition, we assessed the impact of radiation fractionation and chemotherapeutic regimen on timing. Methods: Randomized trials published after 1985 addressing timing of RT relative to chemotherapy in LS-SCLC were included. Trials were analyzed by risk ratio (RR), risk difference, and number-needed-to-treat methods. Results: Overall survival (OS) RRs for all studies were 1.17 at 2 years (95% CI, 1.02 to 1.35; P = .03) and 1.13 at 3 years (95% CI, 0.92 to 1.39; P = .2), indicating a significantly increased 2-year survival for ERT versus LRT patients and suggestive of a similar trend at 3 years. Subset analysis of studies using hyperfractionated RT revealed OS RR for ERT versus LRT of 1.44 (95% CI, 1.17 to 1.77; P = .001) and 1.39 (95% CI, 1.02 to 1.90; P = .04) at 2 and 3 years, respectively, indicating a survival benefit of ERT versus LRT. Studies using once-daily fractionation showed no difference in 2- and 3-year OS RRs for ERT compared with LRT. Studies using platinum-based chemotherapy had OS RRs of 1.30 (95% CI, 1.10 to 1.53; P = .002) and 1.35 (95% CI, 1.07 to 1.70; P = .01) at 2 and 3 years, respectively, favoring ERT. Studies using nonplatinum-based chemotherapy regimens had nonsignificant differences in OS. Conclusion: A small but significant improvement in 2-year OS for ERT versus LRT in LS-SCLC was observed, similar to the benefit of adding RT to chemotherapy or prophylactic cranial irradiation. A greater difference was evident for hyperfractionated RT and platinum-based chemotherapy.