Prognostic significance of the non-size-based AJCC T2 descriptors - Visceral pleura invasion, hilar atelectasis, or obstructive pneumonitis in stage IB non-small cell lung cancer is dependent on tumor size

Background: The T2 descriptor for staging non-small cell lung cancer (NSCLC) contains several non-size-based criteria. It remains unknown whether the prognostic significance of these non-size-based criteria is dependent on tumor size. Methods: A total of 10,545 patients with stage IB NSCLC from the California Cancer Registry between 1989 to 2003 were categorized into the following three nonoverlapping criteria: (1) tumor size (T2S); (2) visceral pleura invasion, hilar atelectasis, or obstructive pneumonitis (T2P); and (3) main bronchus involvement : 2 cm from the carina (T2Q. Univariate survival analyses were performed using the Kaplan-Meier method. Multivariate survival analyses were performed using Cox proportional hazards ratios. Results: A total of 51.1% of patients with stage IB NSCLC were staged by T2S, 43.2% by T2P, and 5.7% by T2C; 2,224 stage IB patients (total, 21.1%; 18.9% T2P + 2.2% T2C) had tumors <= 3 cm in size. The 5-year survival rate and the median survival time of these stage IB patients with tumors <= 3 cm in size were as follows: T2P, 51.2% and 64 months, respectively; T2C, 49.0% and 58 months, respectively. These values were similar to the 53.2% 5-year survival rate and 67-month median survival time for patients with stage IA NSCLC (p = 0.40). Cox proportional hazards model revealed T2P of > 3 cm was a poor prognostic factor for survival (vs T2S; hazard ratio [HR], 1.16; 95% confidence interval [CI], 1.08 to 1.24). Conversely, T2P <= 3 cm was a favorable prognostic factor for survival (vs T2S; HR, 0.89; 95% CI, 0.82 to 0.96). T2C was not an independent prognostic factor for survival. Conclusions: Prognostic significance of the non-size-based T2 descriptor T2P is dependent on tumor size.