To investigate the prognostic factors of different subgroups of stage ⅠB non-small cell lung cancer (NSCLC).

The clinical and follow-up data of 138 cases of surgically resected stage ⅠB NSCLC in Department of Thoracic Surgery, Union Hospital, Fujian Medical University between March 2008 and December 2013 were retrospectively analyzed. Based on the seventh edition of lung cancer staging of the Union for International Cancer Control(UICC), then according to tumor size and visceral pleura invasion, the patients were divided into three groups: ⅠB-a group (diameter of tumor ≤ 3cm, with visceral pleura invasion), ⅠB-b group(3cm < diameter of tumor ≤ 5cm, without visceral pleura invasion) and ⅠB-c group (3cm < diameter of tumor ≤ 5cm, with visceral pleura invasion). Kaplan-Meier survival analysis and COX proportional hazard model were adopted to explore the factors affecting the prognosis of NSCLC.

The 3-year overall survival of stage ⅠB NSCLC patients was 88.1%. There were 75 cases in ⅠB-a group, 32 cases in ⅠB-b group and 31 cases in ⅠB-c group, and the 3-year overall survival were 92.0%, 90.6% and 74.1%, respectively. There were significant differences in survival among three groups (χ²=6.784, P=0.034). Univariate analysis indicated that the gender (χ²=0.103, P=0.567), age (χ²=2.463, P=0.117), surgical resection(χ²=0.809, P=0.368), postoperative adjuvant chemotherapy (χ²=0.077, P=0.791), tumor′s location (χ²=0.091, P=0.674) and visceral pleura invasion(χ²=0.085, P=0.771) were not statistically significant, while tumor size (χ²=13.937, P=0.007) and tumor differentiation(χ²=21.198, P=0.000) were statistically significant. Further multivariate analysis revealed that only the poor differentiation (RR=0.027, 95% CI: 0.065-0.666, P=0.003) and moderate differentiation(RR=1.627, 95% CI: 1.020-2.597, P=0.008) were statistically significant.

There are significant differences in 3-year overall survival among subgroups of stage ⅠB NSCLC, and there is room for improvement in TNM staging for definition of ⅠB stage. Tumor size and tumor differentiation are important factors affecting the 3-year overall survival, moreover, the poor and moderate differentiation are independent factors, while the postoperative adjuvant chemotherapy has no effect on the 3-year overall survival. The findings need further investigations to confirm.