SUNDAY, April 13 (HealthDay News) — Alcohol, consumed even in small amounts, increases the risk of breast cancer and particularly estrogen-receptor and progesterone-receptor positive breast cancer, a new study shows.
Previous data has suggested that consuming alcohol ups the risk of breast cancer, although the precise mechanisms have not been clarified.
In the study, a team led by Dr. Jasmine Lew of the U.S. National Cancer Institute followed more than 184,000 postmenopausal women for an average of seven years.
Those who had less than one drink a day had a 7 percent increased risk of breast cancer compared to teetotalers, the team reported. Women who drank one to two drinks a day had a 32 percent increased risk, and those who had three or more glasses of alcohol a day had up to a 51 percent increased risk.
But the risk was seen mostly in those 70 percent of tumors classified as estrogen receptor- and progesterone receptor-positive. Researchers suspect that alcohol may have an effect on breast cancer via an effect on estrogen.
The risk was similar whether women consumed primarily beer, wine or spirits, the NCI team noted.
The second study dug deeper into other possible mechanism by which alcohol consumption increases breast cancer risk.
"For years, we've known that there's an association between alcohol drinking and breast cancer risk, but nobody knows yet what the underlying biological mechanisms are," said Dr. Catalin Marian, lead author of the study and a research instructor in oncology at the Lombardi Comprehensive Cancer Center at Georgetown University in Washington, D.C. "The logical step was to begin analyzing the alcohol metabolizing genes."