Bcl-2 is a useful prognostic marker in Dukes' B colon cancer

Background: Currently, the use of adjuvant therapy specifically in Dukes' B colon cancers is controversial, emphasizing the importance of identifying prognostic markers to select patients for such therapy. Bcl-2 plays an impo rtant role in apoptosis regulation of solid tumors, such as colon and breas t cancer, and is normally expressed in the base of the colonic crypts. The purpose of this study is to determine whether or not bcl-2 expression can b e used to predict survival in Dukes' B colon cancer patients. Methods: Charts of 76 patients operated on at the Royal Victoria Hospital f rom 1986 to 1992 were reviewed. Bcl-2 staining was done with the avidin-bio tin-peroxidase complex method using commercially available monoclonal bcl-2 antibodies. Two pathologists graded the intensity of bcl-2 staining on a s cale of 0-3 and estimated the percentage of tumor cells staining positively (T-percent). Univariate and multiple regression of factors on overall surv ival (OS) and disease-free survival (DFS) was done with a Cox proportional hazards model and Kaplan-Meier survival curves. Results: The mean age was 71.2 years, with 41 female and 35 male patients. Mean tumor size was 5.4 cm with tumor grades of 19 well, 52 moderate, and 5 poorly differentiated. Tumors expressing bcl-2 had a similar DFS (P =.14) but a significantly improved OS (P =.04) compared with the bcl-2 negative t umors. The risk ratio for DFS was 0.49 (95% CI, 0.19-1.26) and for OS was 0 .35 (95% CI, 0.13-0.94). Conclusions: These data indicate that enhanced bcl-2 expression, specifical ly in Dukes' B colon carcinomas, is associated with improved survival. Thus , patients whose tumors do not express bcl-2 should be considered for adjuv ant therapy.