Alcohol before pregnancy linked to increased risk of breast cancer

September 10, 2013 | by

Young women may want to think twice before having a glass of wine with their dinner or a beer at the end of the day. A new study has found an increased risk of breast cancer among women who regularly consumed alcoholic beverages in the years between the start of menstruation and first pregnancy.

Alcohol years before pregnancy is linked to an increased risk of breast cancer. City of Hope expert urges that actual statistical risk be considered.

Consuming alcohol years before pregnancy is linked to an increased risk of breast cancer. City of Hope expert points out that the actual statistical risk should be considered.

In an analysis of data from more than 91,000 women, researchers at Washington University School of Medicine in St. Louis found that females who consumed just one alcoholic drink a day — one bottle of beer, a 4-ounce glass of wine or a shot of liquor — before their first pregnancy increased their risk of being diagnosed with breast cancer by 11 percent. They increased their risk of proliferative benign breast disease by 16 percent. Many previous studies have linked alcohol consumption to breast cancer, but researchers noted that this study is one of the first to focus primarily on the effect of alcohol intake before a first pregnancy.

But, noting the nature of statistics, Laura Kruper, M.D., director of the Rita Cooper Finkel and J. William Finkel Women’s Health Center at City of Hope, said that women and their doctors must keep the 11 percent increased risk in perspective. A women’s overall lifetime risk of breast cancer is about 12 percent.

“If you take the baseline risk — 12 percent — and increase that by 11 percent, it is about 13 percent,” Kruper said in an interview with HealthDay.

The study, published in the Journal of the National Cancer Institute, is based on women who were part of the Nurses’ Health Study II from 1989 to 2009. Researchers analyzed the women’s reporting of their own alcohol consumption and assessed the potential connection to the risk of breast cancer and proliferative benign breast disease, which raises the risk of breast cancer.

After analyzing the data and taking factors such as a family history of breast cancer into account, the researchers found more than 1,000 cases of breast cancer and 970 diagnosis of benign breast disease.

Drinking alcohol after the first menstrual period and before the first pregnancy was linked with a risk of both breast cancer and benign breast disease, regardless of a woman’s drinking habits after the first pregnancy.

“Our results suggest that alcohol intake before the first pregnancy consistently increases the risk of breast cancer and the risk of proliferative [benign breast disease],” the study’s lead author, Ying Liu, M.D., Ph.D., said in an interview with HealthDay. "These risk values were estimated as compared with nondrinkers."

The results didn’t find a causative connection, of course, only a correlation.

But both Kruper and Liu agreed that another call for drinking moderation in young women is in order.

"I think the real take-home point is the more you drink the more you increase risk," said Kruper.