A pooled analysis of limited-stage small-cell lung cancer patients treated with induction chemotherapy followed by concurrent platinum-based chemotherapy and 70 Gy daily radiotherapy: CALGB 30904.

INTRODUCTION: Standard therapy for limited-stage small-cell lung cancer (L-SCLC) is concurrent chemotherapy and radiotherapy (RT) followed by prophylactic cranial radiotherapy. Although many consider the standard RT regimen to be 45 Gy in 1.5 Gy twice-daily fractions, this has failed to gain widespread acceptance. We pooled data of patients assigned to receive daily RT of 70 Gy from three, consecutive prospective Cancer and Leukemia Group B L-SCLC cancer trials and report the results here.

METHODS: All patients from consecutive Cancer and Leukemia Group B L-SCLC trials (39808, 30002, and 30206) using high-dosage daily RT with concurrent chemotherapy were included, and analyzed for toxicity, disease control, and survival. Overall survival (OS) and progression-free survival (PFS) were modeled using Cox proportional hazards models. Prognostic variables for OS-rate and PFS-rate were assessed using logistic regression model.

RESULTS: Two hundred patients were included. The median follow-up was 78 months. Grade 3 or greater esophagitis was 23%. The median OS for pooled population was 19.9 months (95% confidence interval [CI]: 16.7-22.3), and 5-year OS rate was 20% (95% CI: 16-27%). The 2-year PFS was 26% (95% CI: 21-32%). Multivariate analysis found younger age (p = 0.02; hazard ratio [HR]: 1.023; 95% CI: 21-32), and female sex (p = 0.02; HR:0.69; 95% CI: 0.50-0.94) independently associated with improved overall survival.

CONCLUSION: Two-Gy daily RT to a total dosage of 70 Gy was well tolerated with similar survival to 45 Gy (1.5 Gy twice-daily). This experience may aid practitioners decide whether high-dosage daily RT with platinum-based chemotherapy is appropriate outside of a clinical trial.