Alcohol intake trajectories during the life course and risk of alcohol-related cancer in a prospective cohort study.

Aims: Although ethanol in alcoholic beverages and its metabolite acetaldehyde are established carcinogens, the effect of different patterns of alcohol intake over the lifetime has rarely been investigated. We examined associations between sex-specific alcohol intake trajectories and alcohol-related cancer risk using data from 22,756 women and 15,701 men aged 40-69 years at baseline in the Melbourne Collaborative Cohort Study. Methods : Alcohol intake for 10-year periods from age 20 until the decade encompassing recruitment, calculated using recalled beverage-specific frequency and quantity, was used to estimate group-based sex-specific intake trajectories. Incident primary invasive cancers of the upper aerodigestive tract, breast, liver and colorectum were defined as "alcohol-related cancer". Hazard ratios (HR) and 95% confidence intervals (CI) for incident alcohol-related cancer were estimated, adjusted for potential confounders. Results : Six distinct alcohol intake trajectories for men and three for women were identified. A total of 2303 incident alcohol-related cancers were diagnosed during 485,525 person-years in women and 789 during 303,218 person-years in men. Compared with "stable low" intake (maximum < 0.5 g/day at each data point), heavy intake (median>=60 g/day) at age 20-39 followed by either an early (from age 40-49) (early decreasing heavy; HR = 1.75, 95% CI: 1.25-2.44) or late decrease (from age 60-69) (late decreasing heavy; HR = 1.94, 95% CI: 1.28-2.93), and moderate intake (median = 30-59 g/day) at age 20-39 increasing to heavy intake from age 40-49 (increasing heavy; HR = 1.45, 95% CI: 1.06-1.97) were associated with increased risk of alcohol-related cancer for men. For women, increasing intake from age 20 to age at baseline was associated with increased risk of alcohol-related cancer (increasing moderate; HR = 1.25, 95% CI: 1.06-1.48). Associations largely remained consistent for men and women in analyses for colorectal and breast cancer, respect