['The basic premise of CT screening is that size is an important determinant of survival in lung cancer. We sought to examine this hypothesis within stage IA non-small cell lung cancer (NSCLC).', 'A retrospective analysis of all patients with pathologically confirmed stage IA NSCLC resected from 1991 to 2001 was conducted. All but seven patients underwent anatomic lung resection and mediastinal lymph node dissection. Kaplan-Meier survival analysis was performed to estimate the 5-year overall and disease-specific survival probability stratified by tumor size. The influence of age, gender, histology, and tumor size on survival was also analyzed using a Cox proportional hazards regression model.', 'There were 244 patients (mean age, 66.7 years; 45.1% were men). Lobectomy was performed in 229 patients, segmentectomy in 8 patients, and wedge resection in 7 patients. Operative mortality was 0.4%. Histologic breakdown was as follows: adenocarcinoma (59.4%), squamous (18.9%), bronchoalveolar (15.2%), large cell (4.5%), and poorly differentiated (2.0%). The median follow-up time for all patients was 2.6 years. The 5-year survival probability for all patients was 71.1% (95% confidence interval [CI], 63.6 to 78.6%). For 161 patients with tumor sizes < or = 2.0 cm, the 5-year survival probability was 77.2% (95% CI, 68.6 to 85.8%) in comparison with 60.3% (95% CI, 46.7 to 73.8%) in 83 patients with tumor size > 2.0 cm (p = 0.03 by log-rank test). The overall 5-year disease-specific survival was 74.9% (95% CI, 67.6 to 82.2%). Disease-specific survival was 81.4% (95% CI, 73.3 to 89.4%) for patients with tumors < or = 2.0 cm and 63.4% (95% CI, 49.6 to 77.1%) for patients with tumors > 2.0 cm.'] Does tumor size predict survival within stage IA non-small cell lung cancer?