To the Editors: We read with interest the article by Li and Daling in which the authors reported that invasive ductal carcinoma and invasive lobular carcinoma incidence rates fell steadily from 1998 to 2004. The authors attributed these declines primarily to saturation of screening and secondarily to the widespread cessation of hormone use, which started in 2002 (1).
However, the authors made no reference to other established risk factors that could have changed during the study period, particularly the declining consumption of alcohol in the United States. Alcohol is an established, dose-dependent, risk factor for the development of estrogen receptor–positive breast cancer (2) and could be a contributing factor to the authors' observations. Alcohol consumption has been declining for decades in the United States. The National Institute on Alcohol Abuse and Alcoholism reported that the per capita consumption of alcohol by Americans had steadily declined by 10% from 1990 to 2000 and this trend seems to continue (3). The Harvard School of Public Health College Alcohol Study's survey documented an increase in the proportion of female college student abstainers and a decrease in the average number of drinks consumed by those who do drink in 2002 (4).
By contrast, we have not observed such a decline in invasive breast cancer incidence rates in the United Kingdom despite the saturation of the national screening program and widespread publicity associated with the Women's Health Initiative findings (5). In the southeast of England where incidence statistics are available,1
We thank the Thames Cancer Registry for providing the breast cancer incidence data for the southeast of England.