Alcohol and Cancer in Women: Results of a Large Prospective UK Study

A UK study based on a cohort of more than 1 million women related baseline alcohol intake to the relative risk (RR) of incident invasive cancer at 21 sites. A quarter of the cohort reported drinking no alcohol; 98% of those who drank consumed fewer than 21 drinks per week and had an average consumption of 10 g of alcohol per day (1 standard drink as defined in this study). Only current drinkers were included in dose-response analyses; both lifetime abstainers and ex-drinkers were excluded. During an average of 7.2 years of follow-up, 68,775 invasive cancers occurred. Results included the following:

• Increased alcohol consumption was associated with increased risk of cancers of the oral cavity and pharynx (increase in RR per 10 g daily increase in alcohol intake, 29%), esophagus (22%), larynx (44%), rectum (10%), liver (24%), breast (12%), and total cancer (6%).

• For cancers of the upper aerodigestive tract, alcohol-associated risk was confined to current smokers, with little or no effect among never or past smokers.

• Increased alcohol consumption was associated with a decreased risk of thyroid cancer, non-Hodgkin lymphoma, and renal cell carcinoma.

• Trends were similar in women who drank wine exclusively compared with consumers of other types of alcohol.

• For every additional drink regularly consumed per day, the increase in incidence up to age 75 years per 1000 women in developed countries was estimated to be about 11 for breast cancer; 1 for cancers of the oral cavity and pharynx; 1 for cancer of the rectum; and 0.7 each for cancers of the esophagus, larynx, and liver.

Comments:

The results of this study support what has been known for many decades: there is an association between alcohol intake, especially heavy intake, and upper aerodigestive cancers. Further, even moderate drinking may increase the risk of other cancers, including breast cancer. There are, however, a number of analytic problems with this paper: the authors were unable to compare results of current drinkers with lifetime abstainers and ex-drinkers separately; no data were provided on pattern of drinking (regular or binge); and only linear analysis was used, making it difficult to judge if the association between alcohol and these cancers was U-shaped, J-shaped, or showed a threshold effect. While it is important to emphasize that alcohol can be associated with cancer, it will be especially important for additional studies based on this large cohort to report the net effects of drinking on other diseases and on total mortality. R. Curtis Ellison, MD

Reference:

Allen NE, Beral V, Casabonne D, et al. Moderate alcohol intake and cancer incidence in women. J Natl Cancer Inst. 2009;101(5):296–305.