Can drinking pre-pregnancy increase risk of breast cancer?

A recent study finds that women who drink even one alcoholic beverage per day before their first pregnancy are at greater risk of developing breast cancer. The study also linked delayed childbirth with an increased risk of the disease.

“The longer the duration between a woman’s first period and her first pregnancy, the greater her risk of breast cancer in general,” says Dr. Melissa Miller-Carter, obstetrician/gynecologist on staff at Advocate Sherman Hospital in Elgin, Ill. “Adding alcohol to the mix provides a “fuel-to-the-fire” effect.”

According to the study, published in the Journal of the National Cancer Institute, 10 grams a day of alcohol (about six drinks per week) increases a woman’s risk of breast cancer by 11 percent compared to non-drinkers. One alcoholic beverage per day was also linked to a greater risk of proliferative benign breast disease, which can be a risk factor for breast cancer.

“Alcohol is a carcinogen and can stimulate cellular changes within the body,” Dr. Miller-Carter explains. “As such, it may increase the risk of not just breast cancer but many types of cancer, though the magnitude of that role has yet to be elicited.”

The study followed data from more than 91,000 women who were analyzed from 1989-2009. The women, who did not have any history of cancer, were asked questions about their alcohol consumption to determine a link between drinking and breast cancer development in the future. In addition, the study followed another group of more than 60,000 women evaluated from 1991-2001 to determine if alcohol consumption was linked to the development of benign breast disease.

During the study, 1,600 women were diagnosed with breast cancer and 970 were diagnosed with benign breast disease. Researchers concluded that pre-pregnancy drinking was linked to an increased risk of both diseases.

In addition to alcohol consumption, there is a link between breast cancer and delayed childbirth, researchers said. A woman’s breast tissue in the timeframe between the first menstruation and first pregnancy may be more susceptible to carcinogens. In comparison, during pregnancy, a woman’s breast tissue experiences cellular changes that make the tissue less prone to cancer.

“The process of breastfeeding is protective on the breast tissue,” Dr. Miller-Carter explains.

Dr. Miller-Carter acknowledges that avoiding a martini or glass of wine does not guarantee prevention of breast cancer.

“There are a lot of risk factors in regard to the development of breast cancer, especially family history,” Dr. Miller-Carter says. “Patients with excess alcohol usage can be at a higher risk of any type of cancer, and they should be counseled appropriately. But no study suggests that a patient will not get breast cancer by avoiding alcohol. Cancer, in general, is a multifactorial disease process. We are learning more every day, but surveillance and physician-patient communication are key in truly assessing an individual’s risk.”