Background: Node-positive (TNM stage III) adenocarcinoma of the colon and rectum consists of tumors with a widely variable prognosis. To predict the outcome of patients with stage III carcinoma, we assessed the survival impact of the number and level of lymph node metastasis and other clinicopathological variables.
Study design: A retrospective study was performed on 538 patients with stage III carcinoma of the colon and rectum who underwent curative resection at Chang Gung Memorial Hospital between 1980 and 1989. Ten or more lymph nodes in each resected specimen were identified microscopically. Multivariate analysis was used to determine the independent variables.
Results: The relative survival rates at five and ten years were 52 and 42 percent, respectively. Tumor morphology, depth or tumor penetration, histologic grade, and the status (number and level) of nodal involvement were significant in the univariate analyses. Only grade and nodal status remained significant in the multivariate analysis. Based on the nodal status, these patients were separated into three groups: stage IIIA (one to three positive nodes and absence of pN3 metastasis), IIIB (four to nine nodes and absence of pN3), and IIIC (ten or more nodes or presence of pN3). The five-year survival rates for patients with stages IIIA, IIIB, and IIIC disease were 69, 44, and 29 percent, respectively. Compared with patients with stage IIIA disease, the odds of death for patients with stages IIIB and IIIC carcinoma were 2.1 (95 percent confidence interval: 1.5 to 2.8, p = 0.0001) and 3.3 (95 percent confidence interval 2.4 to 4.5, p = 0.001), respectively.
Conclusions: We suggest that stage III adenocarcinoma of the colon and rectum be divided into three substages: IIIA (one to three positive nodes and absence of pN3 metastasis), IIIB (four to nine nodes and absence of pN3), and IIIC (ten or more positive nodes or presence of pN3.