TNM classification and prognostic factors of 1 368 patients with colorectal cancer

Objective: To assess the survival rates of patients with different TNM stages, and to explore the prognostic factors of colorectal cancer. Methods: A total of 1,368 cases of colorectal cancer operated and pathologically confirmed at the Second Affiliated Hospital of Zhejiang University School of Medicine from 1985 to 2005 were collected. All cancers were pathologically staged according to AJCC TNM classification (seventh edition). Univariate and multivariate analyses were applied to evaluate the prognostic factors. For univariate analysis, the cumulative survival rate was calculated using the Kaplan-Meier method, and the significant difference was evaluated by the log-rank test. Cox multivariate regression analysis was performed to identify the predictors of survival. All these analyses were conducted using SPSS software (version 19.0). Results: The 3-, 5-, and 10- year overalll survival rates were 67.5%, 60.2%, and 53%, respectively. The survival rates for 3, 5, and 10 years after radical resection were 77.6%, 69.9%, and 62.4% respectively. According to the TNM classification, the 5-year survival rates of the stage- I, -II, -III, and -IV patients were 90.1%, 72.6%, 53.8%, and 10.4%, respectively. Multivariate analysis by Cox regression revealed that the following factors were independently associated with the cumulative survival rate of colorectal cancer: depth of invasion, lymph node metastasis, total number of lymph nodes, adjacent organ involvement, metastasis, radical resection, and post-operative infection. The 5-year overall survival rate was lower in stage- II C patients than in stage- III A or - III B patients. The survival curves of the above factors were significantly different (P < 0.05). Conclusion: The depth of invasion, lymph node metastasis, total number of lymph nodes inspected after surgery, adjacent organ involvement, metastasis, radical resection, postoperative infection are the independent prognostic factors of colorectal cancer. The depth of invasion may be a more precise prognostic factor for stage- II and - III patients.