Impact of thoracic radiotherapy timing in limited-stage small-cell lung cancer: usefulness of the individual patient data meta-analysis†

International audience; BackgroundChemotherapy combined with radiotherapy is the standard treatment of “limited-stage” small-cell lung cancer. However, controversy persists over the optimal timing of thoracic radiotherapy and chemotherapy.Material and methodsWe performed a meta-analysis of individual patient data in randomised trials comparing earlier versus later radiotherapy, or shorter vs. longer radiotherapy duration, as defined in each trial. We combined the results from trials using the stratified log-rank test to calculate pooled hazard ratios (HRs). The primary outcome was overall survival.ResultsTwelve trials with 2,668 patients were eligible. Data from nine trials comprising 2,305 patients were available for analysis. The median follow-up was 10 years. When all trials were analysed together, “earlier or shorter” vs. “later or longer” thoracic radiotherapy did not affect overall survival. However, the HR for overall survival was significantly in favour of “earlier or shorter” radiotherapy among trials with a similar proportion of patients who were compliant with chemotherapy (defined as having received 100% or more of the planned chemotherapy cycles) in both arms (HR 0.79, 95% CI 0.69–0.91) and in favour of “later or longer” radiotherapy among trials with different chemotherapy compliance (HR 1.19, 1.05–1.34, interaction test p