The effect of radiotherapy dose on survival in stage iii non-small-cell lung cancer patients undergoing definitive chemoradiotherapy

Background In this study, we examined trends in the radiotherapy dose prescribed and the effect of dose escalation on survival in patients with stage III lung cancer.

Materials and Methods Radiation dose prescription patterns were analyzed for 38,848 patients in the National Cancer Database with clinical stage III disease who underwent concurrent chemoradiation between 2004 and 2011 to a dose between 57 and 80 Gy. Survival information was available for patients diagnosed from 2004 to 2006 (n = 12,024). Overall survival (OS) was estimated using Kaplan-Meier methods. Cox proportional hazard regression was used to estimate hazard ratios (HRs).

Results The percentage of patients treated to ≥64 Gy increased from 50% in 2004 to 62% in 2011 (P <.001). The 5-year OS was 12% for patients treated between 57 and 59.3 Gy, 14% for patients treated at 59.4 to 62.9 Gy, 16% for patients treated at 63 to 66 Gy and 66.1 to 73.9 Gy, and 13% for patients treated at 74 to 80 Gy (P <.0001). In multivariate analysis, the estimated HR (95% confidence interval) was 1.3 (1.1-1.6) for 57 to 59.3 Gy, 1.0 (0.9-1.2) for 59.4 to 62.9 Gy, 0.9 (0.9-1.2) for 63 to 66 Gy, 0.9 (0.8-1.1) for 66.1 to 73.9 Gy, and 1.0 (referent) for the 74 to 80 Gy cohort. There was no significant difference in the HR for the dose groups > 59.4 Gy compared with the 74 to 80 Gy cohort.

Conclusion There was no improvement in OS with radiotherapy dose escalation beyond 59.4 Gy for patients with unresectable clinical stage III lung cancer treated with chemoradiation.