[Correlation of invasion, metastasis, and prognosis in low and middle rectal cancer]

Several reports have showed that three histologic variables (venous invasion, regional lymph node status, and depth of primary tumor penetration) were associated with the prognosis of colorectal adenocarcinoma patients. Based on these variables, a new classification system has been recommended. This study was designed to evaluate prognostic significance and risk factors of neoplasm in low and middle rectal cancer.

Four hundreds and eighty-four consecutive patients with low and middle rectal cancer were treated by the abdominoperineal resection (APR) (356 patients) and the low anterior resection(LAR) (128 patients) between 1990 and 1996. To determine the independent prognostic variables, the variables were evaluated both univariately and multivariately from the perspectives of oncologic outcome.

The 5-year survival rate for all patients was 71.1% (344/484), 63.5% (226/356) for APR and 92.2% (118/128) for LAR/SSR, respectively (P < 0.01). The resulting multivariate analysis using Cox regression showed that the three tumor variables were significantly associated with the 5-year survival (P < 0.01), the independent prognostic variables included venous invasion, tumor size, and TNM stages.

The three tumor variables identified in multivariate analysis as bearing the strongest independent effect on the 5-year survival in low and middle rectal cancer were (in order to decrease prognostic impact) venous invasion, tumor size, and TNM stages. These three tumor variables may be used as important bases for a new classification system.