Even moderate drinkers more likely to develop breast cancer

It is already known that too much consumption of alcohol increases the risk of breast cancer. Now, a new study has found that even small amounts of alcohol may aggrandize the risk of breast cancer, a warning for women who have a daily cocktail.

The largest study ever conducted that links alcoholic consumption with types of breast cancer says that alcohol, even consumed in small quantity, seems to boost the risk of breast cancer, particularly estrogen-receptor positive (ER+) and progesterone-receptor positive (PR+) breast cancer in postmenopausal women.

To reach their findings, a team of researchers at U.S. National Cancer Institute looked at 184,000 postmenopausal women and followed them for an average of seven years. The study participants, who were asked about how much alcohol and what type of alcohol they drank each day, reported their alcoholic consumption as less than one drink per day, one to two drinks per day, or three or more drinks per day. After reviewing the data, the researchers identified 70 percent of the women as drinking every day.

Jasmine Q. Lew, a University of Chicago medical student who led the study, said that women who drank one to two drinks a day had a 32 percent increased risk, while those who had three or more glasses of alcohol a day had up to a 51 percent increased risk. On the other hand, women who had less than one drink per day had a 7 percent increased risk of breast cancer compared with those who didn't drink.

A woman's chance of developing the most common form of breast cancer was similar whether she drank beer, wine, or spirits, the study stated.

"Our study shows that not only does a small amount of alcohol significantly increase the risk of breast cancer, it increases the risk of the most common type of breast cancer, responsible for around 70 percent of cases," Lew said.

In response to a query why would drinking boost the risk of hormone-fueled tumors, Lew said, "Our hypothesis is that alcohol interferes with estrogen metabolism, which in turn increases the risk of hormone-sensitive breast cancer."

Previous studies have though suggested that alcohol intake raises the risk of breast cancer, but the precise mechanisms have not been clarified in those works.

Another study, headed by Dr. Catalin Marian, a research instructor in oncology at the Lombardi Comprehensive Cancer Center at Georgetown University in Washington, D.C., focused on possible biological mechanisms that may account for an association between alcohol consumption and breast cancer.

The study, presented at the meeting of the American Association for Cancer Research, shows that specific variations within two genes--ADH1B and ADH1C-- involved in metabolizing alcohol are linked with an increased risk for breast cancer in postmenopausal women.

“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. The logical step was to begin analyzing the alcohol metabolizing genes," said Dr. Marian.