Increased alcohol consumption is a putative colorectal cancer (CRC) risk factor. However, existing data are less conclusive for women than men. Also, to date, relatively few studies have reported alcohol-related CRC risks based on molecularly-defined tumor subtypes. We evaluated associations between alcohol intake and incident CRC, overall and by microsatellite instability (MSI-H or MSI-L/MSS), CpG island methylator phenotype (CIMP-positive or CIMP-negative) and BRAF mutation (mutated or wild-type) status in the prospective, population-based Iowa Women's Health Study (IWHS; n = 41,836). Subjects were 55-69 years at baseline (1986) and exposure data were obtained by self-report. Incident CRCs were prospectively identified and archived, paraffin-embedded tissue specimens were collected from 732 representative cases, diagnosed through December 31, 2002. Multivariate Cox regression models were fit to estimate relative risks (RRs) and 95% confidence intervals (CIs). Among alcohol consumers, the median intake (range) was 3.4 (0.9-292.8) g/day. Compared to non-consumers, alcohol intake levels of < 3.4 g/day (RR = 1.00; 95% CI = 0.86-1.15) and > 3.4 g/d (RR = 1.06; 95% CI = 0.91-1.24) were not significantly associated with overall CRC risk. Analyses based on alcohol intake levels of < 30 g/d and > 30 g/d or quartile distributions yielded similar risk estimates. Null associations were also observed between each alcohol intake level and the MSI-, CIMP- or BRAF-defined CRC subtypes (p > 0.05 for each comparison). These data do not support an adverse effect from alcohol intake on CRC risk, overall or by specific molecularly-defined subtypes, among older women.
- Received May 26, 2011.
- Revision received August 2, 2011.
- Accepted August 16, 2011.
- Copyright © 2011, American Association for Cancer Research.