Alcohol intake and colorectal cancer: A comparison of approaches for including repeated measures of alcohol consumption

BACKGROUND: In numerous studies, alcohol intake has been found to be positively associated with colorectal cancer risk. However, the majority of studies included only one exposure measurement, which may bias the results if long-term intake is relevant. METHODS: We compared different approaches for including repeated measures of alcohol intake among 47,432 US men enrolled in the Health Professionals Follow-up Study. Questionnaires including questions on alcohol intake had been completed in 1986, 1990, 1994, and 1998. The outcome was incident colorectal cancer during follow-up from 1986 to 2002. RESULTS: During follow-up, 868 members of the cohort experienced colorectal cancer. Baseline, updated, and cumulative average alcohol intakes were positively associated with colorectal cancer, with only minor differences among the approaches. These results support moderately increased risk for intake >30 g/d and weaker increased risk for lower intake. The hazard ratio for baseline alcohol intake was 1.07 (95% confidence interval = 1.02-1.11) per 10 g/d increase, which was similar for updated and cumulative average alcohol intake. Consistent moderate and high alcohol intake showed increased risk, and the relative risk decreased slightly with longer latency time. Alcohol frequency was positively associated with cancer risk among men with alcohol intake above 15 g/d. CONCLUSIONS: Alcohol intake was positively associated with colorectal cancer, with minor differences among analytic approaches (which may be attributable to low intraindividual variation during follow-up).