Definitive Radiotherapy for Stage I Nonsmall Cell Lung Cancer

BACKGROUND: The current study characterizes the overall survival (OS) and cause-specific survival (CSS) of patients with stage I nonsmall cell lung cancer (NSCLC) who were treated with radiotherapy alone, and analyzes the variables potentially affecting survival outcomes. METHODS: A total of 8524 patients with stage I NSCLC (according to the sixth edition of the American Joint Committee on Cancer staging manual) who were diagnosed between 1988 and 2008 were retrospectively analyzed using the population-based Surveillance, Epidemiology, and End Results database. Cox regression analysis was used to calculate hazard ratios (HR) from multivariate analyses. RESULTS: The 1-year, 2-year, and 5-year OS rates were 62%, 37%, and 11%, respectively; the corresponding lung cancer CSS survival rates were 68%, 45%, and 20%, respectively. Approximately 77% of deaths were from lung cancer (5292 of 6891 total deaths). Cardiac (n = 477 deaths) and pulmonary (other than lung cancer deaths; n = 475 deaths) deaths accounted for 14% of deaths. From Cox proportional hazards analyses, male sex (HR, 1.2) and squamous cell carcinoma histology (HR, > 1.1) were found to be significantly (P < .0001) adverse prognostic factors for both OS and lung cancer CSS. A more recent calendar year of diagnosis was associated with significantly (P < .0001) improved OS (HR, 0.84 per decade) and lung cancer CSS. This trend was also significant (P < 0.0001) when restricting analyses to those patients with tumors measuring <= 5 cm (n = 5402 patients). T1 classification (vs T2 or T unknown) and smaller tumor size were found to be significantly (P < .0001) favorable factors. CONCLUSIONS: From a population-based registry analysis of patients with stage I NSCLC, significant (albeit modest) improvements in survival in more recent years were appreciated, which likely reflect technologic advances in the diagnosis of, staging of, and radiotherapy for NSCLC. Cancer 2012. (c) 2012 American Cancer Society.