Lifetime Drinking, Confounders, and Breast Cancer Risk
Researchers in New York examined whether confounding factors could explain the association between moderate drinking and an increased risk of breast cancer. Using data from a population-based study, they compared information on alcohol use and other lifetime exposures from 1508 women with breast cancer and 1556 matched controls. Analyses were adjusted for potential confounders (e.g., age at diagnosis, race, education, body mass index [BMI]).
- Breast cancer risk was not significantly associated with lifetime* or current alcohol use, except for current drinking of <0.5 grams per day (odds ratio [OR]** 0.7).
- In subgroup analyses, the relationship between breast cancer risk and lifetime alcohol intake of 15–30 g (approximately 1–2 drinks) per day was significant in women with a BMI <25 (OR 2.1), and who were postmenopausal and had never used hormone replacement therapy (OR 2.0). Further, lifetime drinking of >=15 g per day was significantly associated with estrogen receptor positive tumors (OR 1.9) and invasive tumors (OR 1.6), but only in women with a BMI <25.
- Results did not differ in analyses that examined alcohol intake during a particular decade of life.
These findings are consistent with those of most previous studies that show a weak positive relationship between alcohol use and breast cancer risk. However, there was no dose-response curve for any of the observed associations, and only the subgroup analyses were significant. Additional studies are needed to help clinicians identify women at higher risk of breast cancer from current or lifetime moderate drinking.R. Curtis Ellison, MD
**Odds ratios compare drinking with not drinking alcohol at least once for 6 months or more
Terry MB, Zhang FF, Kabat G, et al. Lifetime alcohol intake and breast cancer risk. Ann Epidemiol. 2006;16(3):230–240.