Impact of Large Tumor Size on Survival After Resection of Pathologically Node Negative (pN0) Non–Small Cell Lung Cancer

Background The current TNM staging system first adopted the tumor size of 3 cm for subdivision of stage I and II disease. The aim of the present study was to evaluate the impact of tumor size on survival in patients with pathologically node negative (pN0) non–small cell lung cancer after complete resection. Methods We retrospectively reviewed the records of 603 patients with pN0 non–small cell lung cancer patients (403 men and 200 women) who underwent a complete resection in five national chest hospitals between 1992 and 1996, with follow-up duration of more than 5 years, and analyzed tumor size and survival. Survival rate was estimated by the Kaplan-Meier method, and differences were compared by log-rank test. For the multivariate analysis, the Cox proportional hazard model was used to identify variables that significantly affected survival. Results There were 355 adenocarcinomas, 208 squamous cell carcinomas, and 40 large cell carcinomas completely resected. No significant prognostic differences were seen among three groups with smaller-sized tumors (≤2 cm [n = 171], 2.1 to 3 cm [n = 202], and 3.1 to 5 cm [n = 170]); however, patients with a tumor size greater than 5 cm (n = 60) showed a significantly worse prognosis. The 5-year survival rates were 79.6%, 72.7%, 68.1%, and 46.6%, respectively, in these four groups. Multivariate analysis showed the tumor size to be an independent prognostic predictor in patients with pN0 tumors. Conclusions We found that a tumor size of greater than 5 cm was an independent prognostic predictor in pN0 disease; therefore, upgrading the T factor of tumor diameter to greater than 5 cm may be necessary in the next reversion of the TNM staging system.