Just couple of glasses of wine a day could raise risk of breast cancer: Study

By Dr. Ananya Mandal, MDNov 7 2011

According to a new major study just two glasses of a wine a day can increase the risk of breast cancer among women by 50%. Researchers also warn that women who drink regularly in their 20s and 30s are far more likely to develop breast cancer in later life, regardless of whether they reduce their alcohol consumption.

The team from Harvard University and Brigham And Women’s Hospital in Boston, Massachusetts, examined the records of 105,986 women aged 30 to 55 who completed surveys on their current drinking habits and how much they drank previously. Over a period of nearly 30 years researchers tracked how many of the women developed breast cancer. The findings, published in the Journal of the American Medical Association, show that women who drank nearly four units a day were 50 per cent more at risk than those women who did not drink.

One of the explanations could be that alcohol raises estrogen levels, and could trigger the growth of tumors. Sarah Williams, health information officer at Cancer Research UK, said, “This study adds to already strong evidence that drinking even small amounts of alcohol increases the risk of breast cancer. Cutting down on alcohol can reduce the chance of developing breast cancer –- as can keeping a healthy weight and being physically active.”

Yet another study shows that genes are not the final determinant of getting breast cancer. The study shows that women who don't test positive for the mutations are not at an extremely high risk of getting breast cancer, even if they have a relative with BRCA-related breast cancer. Their risk is similar to that of women with relatives with non-BRCA-related cancers, the new research indicates.

This refutes a finding from a 2007 study, which found a two- to five-times higher risk for these women, even if they tested negative for the mutations, said senior study author Dr. Alice S. Whittemore, a professor of health research and policy at Stanford University School of Medicine.

Based on the new research, she said, the bottom line is this, “If you are in a family where there is a BRCA mutation and you do not have that mutation, your risk of breast cancer is no greater than anyone with a family history of (other types of) breast cancer.” According to the American Cancer Society, having one first-degree relative, such as a mother, sister or daughter, with breast cancer doubles a woman's risk of getting it. Having two close relatives increases the risk about threefold. Whittemore calls the new finding “very, very reassuring” because it suggests that having a family history of the BRCA mutation, by itself, is not a risk factor, she said.

The study is published online Oct. 31 in the Journal of Clinical Oncology.

Women with a BRCA1 or BRCA 2 gene mutation have a 5- to 20-fold higher risk of getting breast or ovarian cancer, the Stanford researchers wrote. That means a lifetime probability of up to 65 percent for breast cancer, and up to 40 percent for ovarian cancer. Women who have the BRCA1 and BRCA2 mutations and are cancer-free are urged to step up their screening and to begin it early, by age 25, among other measures. They may also consider a preventive mastectomy or ovary removal after childbearing is done.

However, the 2007 study, Whittemore said, “sent an alarm signal to the medical community” as it suggested a high risk even in BRCA-negative relatives. “What we thought to be the flaw was that they were comparing these relatives of women with breast cancer to the general population. A better comparison group would have been women who have relatives with breast cancer but no mutation,” Whittemore said. “That's what we did.”

The new study looked at 3,047 families from the United States, Australia and Canada. It included 160 families with BRCA1 and 132 with BRCA 2. The researchers compared cancer risk in women who tested negative but had relatives with BRCA-related breast cancer with a group of cancer-free women who had relatives with cancer that wasn't BRCA-related. They found no increased risk for the women who were BRCA-negative and had close relatives with BRCA-related cancer.

Besides BRCA1 and BRCA2 mutations, other risk factors, not totally understood, that can run in families also drive breast cancer risk, experts say. One example is drinking habits. The findings suggest that BRCA-negative women can follow the same breast cancer screening routine as the general population, if they have no other strong risk factors, Whittemore said.

The findings should be reassuring to women without the mutation, agreed Dr. Patricia Ganz, director of cancer prevention and control research at the University of California's Jonsson Comprehensive Cancer Center. “The main message,” she said, “is that these women (without the mutation) don't need all that extra surveillance.”