A Prospective cohort study in Denmark tested the hypothesis that postmenopausal women who increase their alcohol intake over a five year period have a higher risk of breast cancer and a lower risk of coronary heart disease compared with stable alcohol intake.
The study included 21,523 postmenopausal women who participated in the Diet, Cancer, and Health Study in two consecutive examinations in 1993-98 and 1999-2003. Information on alcohol intake was obtained from questionnaires. Incidence of breast cancer, coronary heart disease, and all cause mortality during 11 years of follow-up were measured and hazard ratios were calculated according to five year change in alcohol intake.
During the follow up period there were 1,054 cases of breast cancer, 1,750 cases of coronary heart disease, and 2,080 deaths. Women who increased their alcohol intake over the five year period had a higher risk of breast cancer and a lower risk of coronary heart disease than women with a stable alcohol intake. Women who increased their alcohol intake by 7 or 14 drinks per week (corresponding to one or two drinks more per day) had hazard ratios of breast cancer of 1.13 (95% confidence interval 1.03 to 1.23) and 1.29 (1.07 to 1.55), respectively, compared to women with stable intake, after adjustment for age, education, body mass index, smoking, Mediterranean diet score, parity, number of births, and hormone replacement therapy. For coronary heart disease, corresponding hazard ratios were 0.89 (0.81 to 0.97) and 0.78 (0.64 to 0.95), respectively, after adjustment for age, education, body mass index, Mediterranean diet score, smoking, physical activity, hypertension, elevated cholesterol, and diabetes.
Results among women who reduced their alcohol intake over the five year period were not significantly associated with a reduced risk of breast cancer or coronary heart disease. Analyses of all cause mortality showed that women who increased their alcohol intake from an already high intake (>/= 14 drinks per week) to an even higher intake had a higher mortality risk that women with a stable high intake.
The researchers state that the study results support the hypotheses that higher levels of alcohol intake are associated with an increased risk of breast cancer and decreased risk of coronary heart disease.
Source: Five year change in alcohol intake and risk of breast cancer and coronary heart disease among postmenopausal women: prospective cohort study. Dam MK; Hvidtfeldt UA; Tjonneland A; Overvad K; Gronbaek M; Tolstrup JS. BMJ, Vol 353, Art No i2314, 2016, 10pp.