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

BackgroundThe 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.MethodsA 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 (T2C). Univariate survival analyses were performed using the Kaplan-Meier method. Multivariate survival analyses were performed using Cox proportional hazards ratios.ResultsA 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.ConclusionsPrognostic significance of the non–size-based T2 descriptor T2P is dependent on tumor size.