ASPIRIN USE AND P53 EXPRESSION IN COLORECTAL-CANCER

p53 protein overexpression indicates loss of tumor suppressor activity and is the most common genetic alteration in colorectal neoplasms. Ep idemiologic and experimental studies suggest that regular use of aspir in may reduce colorectal cancer risk. We set out to determine whether p53 overexpression of the colorectum was associated with a patient's h istory of aspirin use. Self-administered questionnaires, including inf ormation on aspirin use, were obtained from 163 patients with nonfamil ial colorectal cancer and from 326 healthy controls. Nuclear p53 prote in overexpression using anti-p53 CM-1 polyclonal antibody was observed in 44.8% (73/163) of patients' tumors. A nonsignificant inverse assoc iation was observed between use of aspirin and colorectal cancer. Comp ared with that for nonusers, the odds ratio (OR) for individuals who t ook aspirin at least twice weekly was 0.68 (95% confidence interval [9 5% CI]: 0.39-1.18). The odds ratio for those individuals who used aspi rin for less than 5 years was 0.54 (95% CI: 0.24-1.23), and 0.80 (95% CI: 0.42-1.51) for those who used aspirin for 5 years or more, when co mpared with nonusers. An inverse association of regular aspirin use (t wo times per week or more) was found both for cases with p53 overexpre ssion (OR: 0.79; 95% CI: 0.39-1.59), and for cases without p53 overexp ression (OR: 0.56; 95% CI: 0.25-1.22). There was Little evidence of a difference in the effect of aspirin use on cancer risk between cases w ith and without p53 overexpression, even after adjustment for potentia l confounders.