The relationship between statins and colorectal cancer stage in the Women's Health Initiative.

Abstract

1540 Background: Statins are the most widely prescribed cholesterol-lowering drugs in the United States. The anti-carcinogenic effect of statins may reduce the metastatic potential of cancer cells leading to ‘stage migration’ with users more likely diagnosed with early rather than late stage cancer. We evaluated the relationship between prior statin use and colorectal cancer (CRC) stage at diagnosis in the Women’s Health Initiative (WHI). Methods: The study population included 132,322 post-menopausal women aged 50-79 years, among which there were 2,628 pathologically confirmed cases of insitu (3.3%), local (43.6%), regional (40.4%) and distant (12.7) stage CRC, after an average of 13.9 (SD = 4.7) years of follow-up. To reduce the possibility of detection bias among women more likely to be prescribed statins, we excluded women who did not report a mammogram within 5 years of study entry and who had no health insurance or medical care provider (n = 28,237). Stage was coded using criteria implemented in the Surveillance, Epidemiology and End Results (SEER) Program into early (in situ and local) vs. late (regional and distant) stage disease. Information on statin use prior to diagnosis was collected by self and interviewer-administered questionnaires at baseline and at one, three, six and nine years post-baseline. Self- and interviewer-administered questionnaires were used to collect risk factor information. Hazards ratios (HR) and 95% confidence intervals (CIs) evaluating the relationship between statin use at baseline only, and in a time-dependent manner, and diagnosis of late-stage CRC were computed from multivariable-adjusted Cox proportional hazards analyses. Statistical tests were two-sided. Results: Statins were used by 10,868 women (8%) at baseline. There was no significant relationship between statin use at baseline and late stage CRC cancer (HR = 1.03, 95% CI (0.82-1.30) and no significant association by type of statin or duration of use. In the multivariable-adjusted time-dependent model, use of statins was associated with a reduction in diagnosis of late-stage colorectal cancer (HR 0.79, 95% CI 0.67-0.94, p = 0.007). Conclusions: Prior statin use may have an influence on colorectal cancer stage at diagnosis.