Does Tumor Size Improve the Accuracy of Prognostic Predictions in Node-Negative Gastric Cancer (pT1-4aN0M0 Stage)?

BACKGROUND: The prognostic importance of tumor size in gastric cancer is unclear. This study investigated whether the inclusion of tumor size could improve prognostic accuracy in node-negative gastric cancer. METHODS: Clinical and pathological data of 492 patients with node-negative gastric cancer who underwent radical surgery in our department from January 1995 to December 2008 were analyzed. The prognostic accuracy of T stage was compared with that of T stage plus tumor size. The ability of tumor size to improve the 95% confidence interval (CI) of postoperative 5-year survival rate in gastric cancer patients was assessed. Different T stages plus tumor size were further analyzed to assess improvements in prognosis. RESULTS: Mean tumor size was 3.79±1.98 cm with a normal distribution. Multivariate analysis showed that tumor size and T stage were independent prognostic factors. Postoperative 5-year survival rate tended to decrease as tumor size increased in 1 cm increments. The addition of tumor size to T stage improved accuracy in predicting 5-year survival by 4.2% (P<0.05), as well as improving the 95% CI of postoperative 5-year survival rate by 3.2–5.1%. The addition of tumor size improved the predictive accuracy of postoperative 5-year survival rate by 3.9% (95% CI 70.4%–91.1%, P = 0.033) in patients with stage T3N0M0 tumors and by 6.5% (95% CI 68.7%–88.4%, P = 0.014) in patients with stage T4aN0M0 tumors. CONCLUSIONS: Tumor size is an independent prognostic factor for survival in patients with node-negative gastric cancer, as well as improving prognostic accuracy in stage T3/4aN0M0 tumors.