The prognostic inhomogeneity of colorectal carcinomas stage III - A proposal for subdivision of stage III

BACKGROUND. The prognosis of patients with Stage III colorectal carcinoma seems to be inhomogeneous. Therefore a subdivision of Stage III was performed. METHODS. Data from 850 patients of the Erlangen Registry of Colo-Rectal Carcinomas and 603 patients of the Study Group Colo-Rectal Carcinoma (SGCRC) with Stage III colorectal carcinoma were analyzed. Three different subdivisions of Stage III were performed according to pT, pN, and pTpN. Observed 5-year survival rates for all possible substages were calculated according to Kaplan-Meier. To compare the predictive value of several possible substages, Brier-Score and receiver operator charcteristics (ROC) analysis were applied. RESULTS. The subdivision according to pT (pTl,2pN1,2 versus pT3 pN1,2 versus pT4 pN1,2) as well as the subdivision according to pN (any pT pN1 vs. any pT pN2) resulted in significant differences of observed 5-year survival rates. However, subdivision according to pT and pN (pT1,2 pN1 vs. pT3,4pN1 and pT1,2pN2 vs. pT3,4 pN2) was found to be superior. The three substages, IIIA, IIIB, and IIIC, identified 10%, 50%, and 40% of the patients with observed 5-year survival rates of 80%, 60%, and 30%, respectively. Using Brier-Score and ROC analysis an increase in predictive power was found, especially for the patients of the Erlangen Registry, but less clearly for SGCRC patients. CONCLUSION. Subdivision of Stage III colorectal carcinoma into three substages according to the pT and pN categories resulted in subgroups which differed significantly in prognosis. This may be important for comparing treatment results, especially in adjuvant treatment and patient care evaluation studies. Cancer 2001; 92:2754-9. (C) 2001 American Cancer Society.