Non-small cell lung cancer (NSCLC) staging is currently being revised by the International Association for the Study of Lung Cancer (IASLC). Among other changes, the revised staging system proposes the subdivision of the T1 tumor (≤ 3 cm) category into the following two subgroups: T1a (≤ 2 cm); and T1b (> 2 cm but ≤ 3 cm). This study investigated the prognostic differences between patients in these two T1 tumor subgroups.
A total of 291 patients with stage IA (T1N0M0) NSCLC who had undergone surgical resection between January 1, 1991, and December 31, 2004, were identified by the cancer registry. The mean and median follow-up times were 62 and 54 months, respectively. The patients were subdivided into T1a and T1b groups. Overall survival (OS) as well as disease-free survival (DFS) periods were determined by retrospective chart review and compared for statistical significance. Patient-specific and disease-specific information was recorded in order to identify possible confounding variables.
When patients were subdivided into T1a (n = 193) and T1b (n = 98) groups, significant differences were observed in both OS (p = .023) and DFS (p = .014). No statistically significant difference was detected in the mean age, pack-year smoking history, or percent predicted FVC or FEV1 between the T1a and T1b groups. In addition, there was no statistically significant difference in the type of surgery or nodal staging performed on the patients in the two groups.
The T1 descriptor should be subdivided at 2 cm to reflect the observed prognostic differences. Our findings agree with the new staging system proposed by the IASLC, revealing its profound applicability to individual institutions.