May 1, 2017
Based on studies that primarily have included data from white women, alcohol consumption is a known risk factor for breast cancer. Now, a study from the UNC Lineberger Comprehensive Cancer Center has found the same risk exists for black women, an understudied group.
Melissa A. Troester, PhD, professor of epidemiology at the UNC Gillings School of Global Public Health and UNC Lineberger member, is senior author of the article, published in the May issue of the journal Cancer Epidemiology, Biomarkers & Prevention.
In the new study, researchers found that black women who drank more than 14 alcoholic drinks per week had a significantly higher risk of invasive breast cancer than did those who drank less. The findings confirmed the link between alcohol consumption and breast cancer risk.
While some breast cancer risk factors – such as age or genetics – are not modified easily, alcohol consumption is one risk factor over which women have control.
“Minority groups often are understudied because they represent a smaller proportion of study populations,” Troester said. “This work avoided that limitation by working with a consortium of many different studies, including more than 20,000 black women. We found that the patterns observed in other studies examining alcohol and breast cancer risk hold in black women, too.”
The researchers analyzed data for 22,338 women from the African American Breast Cancer Epidemiology and Risk (AMBER) consortium, which combines data from four large breast cancer studies. Researchers evaluated alcohol as a risk factor for invasive breast cancer as well as for specific breast cancer subtypes, such as estrogen receptor positive or negative cancer.
“Our study demonstrated there is benefit in creating consortia to focus on understudied groups,” said the study’s first author Lindsay Williams, an epidemiology doctoral student at the Gillings School.
When the research team studied data across all breast cancer subtypes, they found that consuming seven or more alcoholic drinks per week was linked to increased risk of breast cancer across all subtypes. Women who previously drank alcohol, and later stopped, had lower risk than women who reported recent use – indicating that women may be able to reduce their risk by drinking less.
However, Williams and colleagues did find significantly higher risk for some women who never have consumed alcohol. That group also may include women who have other health conditions that can increase risk for breast cancer. The finding may direct additional research.
“In the future, it may be worthwhile to better characterize women who identify as never-drinkers to understand their reasons for abstaining from alcohol,” Williams said.
The researchers underscored that the study is important because it confirms a breast cancer risk that can be decreased through behavioral change.
“Overall, our findings among African-American women mirror those reported in the literature for white women, namely that high levels of alcohol intake – more than one drink per day – are associated with increased breast cancer risk,” Troester said. “Alcohol is an important modifiable exposure, and women who are concerned about their risk of breast cancer could consider reducing levels of exposure.”
Other study co-authors from the Gillings School include Andrew F. Olshan, PhD, Barbara Sorenson Hulka Distinguished Professor in Cancer Epidemiology and chair of the Gillings School’s epidemiology department, and Charles Poole, ScD, associate professor of epidemiology. Olshan is associate director of population sciences at UNC Lineberger.
The study was supported by the National Institutes of Health, the Komen for the Cure Foundation, the Breast Cancer Research Foundation and the University Cancer Research Fund.
A version of this article originally appeared on the UNC Lineberger website.