Bcl-2 protein expression: association with p53 and prognosis in colorectalcancer

Bcl-2 expression in colorectal carcinomas was studied in a series of 224 pa tients and the relation to p53 expression, stage and survival assessed. Bcl -2 expression was down-regulated compared with normal mucosa in 67% (151) o f the cases. In 144 cases staining was positive for p53 (MAB DO7), and 41 o f these 144 p53-positive cases were also bcl-2 positive (28%) comeared with 32 of the remaining 80 p53-negative cases (40%). Survival was significantl y worse (P = 0.01) in the p53-positive cases. Bcl-2-positive cases, includi ng patients in all Dukes' stages, had a slightly better prognosis which was not statistically significant. However, cases at an early stage (Dukes' st ages A and B) and with negative p53 status, had a much better prognosis if they showed bcl-2 protein expression, suggesting that the bcl-2 status itse lf has an effect on prognosis (P = 0.01). Neither bcl-2 nor p53 alone was c orrelated with stage, but when examined by both p53 and bcl-2 status a grou p [bcl-2(+)/p53(-)] with better prognosis was defined. The last group was s ignificantly lower Dukes' stage, with 26 out of 32 cases (81%) being A or B compared with 22 (11%) of the 202 remaining cases (P = 0.004). Thus, eithe r loss of bcl-2 expression or gain of abnormal p53 expression is associated with high stage and poor prognosis. The bcl-2(+)/p53(-) phenotype is simil ar to that of normal mucosa, and these results suggest that such cases repr esent an indolent group at an early stage in the progression of colorectal cancer.