Abstract
Background Stage IA of non–small cell lung cancer (NSCLC) is divided into two subgroups, T1aN0M0
(d ≤ 2 cm) and T1bN0M0 (2 < d ≤ 3 cm), in the International Association for the Study of Lung Cancer, seventh edition
of TNM Classification of Malignant Tumors.
Objective The purpose of this study was the identification of independent clinicopathological
predictors of prognosis of these two subgroups of NSCLC.
Methods Between 1986 and 2005, a cohort of 1,929 cases of stage IA NSCLC in Tian Jin Medical
University Cancer Institute and Hospital were retrospectively analyzed. The impact
of clinicopathological characteristics on patients' survival was investigated.
Results The overall 5-year survival rate was 71.07%. Patients with T1aN0M0 NSCLC had a better
5-year survival than those with T1bN0M0 (73.98 vs. 68.18%, p = 0.0135). The Cox proportional hazard model revealed that the prognostic factors
of T1aN0M0 were intratumoral vessel invasion (p = 0.035) and histologic differentiation (p = 0.004). In patients with T1bN0M0 NSCLC, the prognostic factors were histologic
differentiation (p < 0.01), intratumoral vessel invasion (p < 0.01), removal of 6 or more lymph node stations (p < 0.01), and removal of lymph node station 7 (p < 0.01).
Conclusion Prognostic factors of T1aN0M0 and T1bN0M0 NSCLC are different. In patients with T1bN0M0
NSCLC, 6 or more lymph node stations and lymph node station 7 should be removed.
Keywords
T1aN0M0 - T1bN0M0 - non–small cell lung cancer - prognosis
