Light to Moderate Alcohol Consumption and Cancer Incidence: The Norwegian Women and Health Cohort Study

To investigate the impact of light-moderate (up to 20 g/day) alcohol consumption on incidence of postmenopausal breast, kidney, lung, pancreatic, colorectal, postmenopausal ovarian and postmenopausal endometrial cancer among women.

Participants were 70,932 women aged 41-70 years, randomly recruited in the Norwegian Women and Health (NOWAC) cohort study from 1996 to 2004. We included women who reported that they consumed alcohol. Only postmenopausal women (N = 32,735) were included in the analyses for female cancers. Multivariable Cox proportional hazard models were used to estimate hazard ratios (HR) and 95% confidence intervals (CI).

The mean follow-up was 19 years. The estimated hazard ratio (HR) from each additional 12g/day of alcohol consumption for postmenopausal breast cancer was 1.20 (95% confidence intervals CI: 1.03 to 1.41), and for kidney cancer 0.42 (95% CI: 0.24 to 0.75). The corresponding estimates for postmenopausal breast cancer among women who used menopausal hormone therapy (MHT) were HR = 1.27, 95% CI: 1.05 to 1.54, and among women who never used MHT were HR = 1.12, 95% CI: 0.86 to 1.47. Compared to alcohol consumption of <3.5 g/day, consumption of 3.5-10 g/day revealed for lung cancer inverse association with risk of lung cancer among women who consumed primarily wine (HR = 0.65, 95% CI; 0.43 to 0.88), but not among other drinkers (HR = 1.10, 95% CI; 0.88 to 1.31). No associations were confined for pancreatic, colorectal, ovarian and endometrial cancers.

Women drinking light-moderate alcohol level had a higher risk of postmenopausal breast cancer and a lower risk of kidney cancer incidence. Our results do not support the threshold of up to 1 drink/day as a safe limit for breast cancer, especially for postmenopausal women who use MHT. The inverse relationship found for lung cancer could be explained by the healthier lifestyle correlated with this light-moderate drinking.