"The marked increase in hormonally sensitive breast cancers, including lobular and ER+/PR+ tumors, among women who drink suggests a hormonal basis for the known association between alcohol use and breast-cancer incidence," Li said. "Alcohol is known to increase estrogen levels in the blood, and therefore it could stimulate hormonally sensitive tumors."

The researchers found no association between alcohol use and increased incidence of hormonally insensitive cancers (estrogen-receptor negative and progesterone-receptor negative, or ER-/PR-, tumors). Since these types of tumors can grow independent of estrogen and progesterone, they are unresponsive to hormonal blockers such as tamoxifen and therefore are more difficult to treat.

While alcohol use has been associated with a moderate increase in breast-cancer risk, few studies, until now, have stratified results by histology (cancer type) or hormone-receptor status, Li said.

"This is one of the first studies to evaluate the relationship between alcohol use and breast cancer and how alcohol consumption modifies the risk of different types of breast cancer. While our results suggest that alcohol is strongly associated with hormonally responsive types of breast cancer, they need to be confirmed by other researchers," said Li, also a research assistant professor of epidemiology at the University of Washington School of Public Health and Community Medicine.

Nearly 2,000 western Washington women, ages 65 to 79, were interviewed for the study; half had a history of breast cancer and half did not. Those with a history of breast cancer were identified through Fred Hutchinson's Cancer Surveillance System, a population-based registry of cancer incidence in western Washington. Those who served as controls were identified through
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Contact: Kristen Woodward
kwoodwar@fhcrc.org
206-667-5095
Fred Hutchinson Cancer Research Center
30-Oct-2003