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.
Keywords: Chemoradiation; Dose Escalation; Locally Advanced Lung Cancer; Radiation Therapy.
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