ORAL-CONTRACEPTIVES, REPRODUCTIVE FACTORS AND P53 GENE-EXPRESSION IN COLORECTAL-CANCER

Protective effects of oral contraceptives and high parity on the devel opment of colorectal cancer have been hypothesized. However, the epide miological data are inconsistent, This inconsistency may be due in par t to the biological heterogeneity of colorectal tumors, A recent inves tigation of hepatocellular carcinoma demonstrated an association betwe en lack of p53 expression and oral contraceptive use. We investigated the relationship between oral contraceptive use and other reproductive factors with p53 over-expression in 64 post-menopausal women, 45-86 y ears of age, with non-familial colorectal adenocarcinoma, Fifty per ce nt (32/64) of colorectal tumors displayed nuclear over-expression of p 53 protein, Women with a history of oral contraceptive use were signif icantly less likely to have p53 positive (+) tumors than women who nev er used oral contraceptives (P = 0.02), In contrast, tumors from women who had never been pregnant were more likely to be p53 + compared to tumors from parous women (P = 0.10), These data suggest that oral cont raceptive use and pregnancy are associated with a p53 independent path way in the development of colorectal cancer.