A prospective study of lifetime alcohol consumption and the risk of breast, upper aero-digestive tract and colorectal cancer, and mortality

© 2014 Dr. Harindra Dilantha Madawala Hubert JayasekaraAlcohol consumption is a major risk factor for preventable chronic disease and injury worldwide while ethanol in alcohol is a carcinogen. On the other hand, moderate drinking has an apparent beneficial effect on cardiovascular health and is associated with lower mortality while heavy drinking is associated with higher mortality than abstinence. The evidence comes mainly from epidemiological studies which have measured alcohol consumption close to study enrolment (‘current’ drinking). Intake over a prolonged period of time is likely to correlate more closely with chronic outcomes. Using data from a prospective cohort study of 41,514 people predominantly aged 40-69 years at recruitment in 1990-94, the associations of alcohol consumption for different periods in life (i.e. lifetime, baseline and past) with the risk of mortality, and breast, upper aero-digestive tract and colorectal cancer incidence were assessed. Alcohol consumption was assessed at study enrolment retrospectively for 10-year age periods from age 20 onwards. The participants were followed-up for approximately 15 years. Deaths were identified through national death indices and incident cases of cancer were ascertained via the population cancer registry. Cox regression with age as the time metric was performed to estimate hazard ratios and 95% confidence intervals for the associations of alcohol consumption with mortality and cancer. A curvilinear dose-response relationship between all-cause mortality and alcohol consumption irrespective of the period of intake was observed with lower mortality at low levels of intake compared with abstention. An increased mortality risk at higher levels of intake was evident for men. Consistent moderate drinking between age 20-29 and current age was also associated with lower mortality for men while consistent heavy drinking over time was associated with higher mortality, compared with consistent abstention. For men, the model using lifetime intake gave a better fit to the data than the model using baseline intake while both models gave similar fits for women. Incidence of breast cancer showed a weak dose-dependent association with lifetime alcohol intake while breast cancer risk did not increase with increasing baseline alcohol consumption. A dose-dependent association between lifetime alcohol intake and upper aero-digestive tract cancer incidence was observed while baseline intake was also positively associated with the incidence of upper aero-digestive tract cancer. Lifetime intake gave a slightly better fit to the data than baseline intake. A positive association between lifetime alcohol intake and colorectal cancer incidence was observed. A higher risk of colorectal cancer with greater alcohol consumption between age 20-29 and baseline that was more prominent for men was also observed. Past intake for age 20-29 for men and lifetime intake for women gave the best fits to the data. In conclusion, moderate lifetime alcohol consumption was associated with lower mortality and heavy drinking from young adulthood to middle-age with higher mortality. Lifetime alcohol intake showed a positive association with breast, upper aero-digestive tract and colorectal cancer incidence. The period of exposure relevant to alcohol as a risk factor for mortality and incidence of breast, upper aero-digestive tract and colorectal cancer extends beyond ‘current’ age. Limiting intake from a young age may reduce the incidence of these cancers. Advice to limit the usual volume of drinking from young adulthood to middle-age should be based on age, risk factors for the particular cancer and cardiovascular disease, and preceding and current alcohol consumption