Alcohol consumption is known to be a risk factor for breast cancer based on studies predominantly done in white women. Now, a University of North Carolina Lineberger Comprehensive Cancer Center study has found the same risk exists for black women, an understudied group.
Researchers found in the new study that black women who drank more than 14 alcoholic drinks per week had a significantly higher risk of invasive breast cancer than those who drank fewer. The findings, published in Cancer Epidemiology, Biomarkers & Prevention, confirmed the link between alcohol consumption and breast cancer risk, which has been seen in other studies drawn from majority white populations.
“Minority groups are often understudied because they represent a smaller proportion of study populations. This work avoided that limitation by working with a consortium of many different studies, including more than 20,000 black women,” says study author Melissa Troester, PhD, a member of UNC Lineberger and professor of epidemiology in the UNC Gillings School of Global Public Health. “We found that the patterns observed in other studies examining alcohol and breast cancer risk hold in black women, too.”
While some breast cancer risk factors—such as age or genetics—aren’t easily modified, alcohol consumption is one risk factor that women, regardless of race, can change to potentially lower their cancer risk.
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. The 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,” says the study’s first author, Lindsay Williams, a graduate research assistant at UNC Gillings.
When they studied the data across all breast cancer subtypes, they found 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 a lower risk than women who reported recent use—indicating that women may be able to reduce their risk by drinking less.
However, researchers did find significantly higher risk for some women who have never consumed alcohol. The researchers said that the group of women that avoids alcohol also sometimes includes women who have other health conditions, and some of these health conditions can increase the risk for breast cancer. The finding may lead to additional research.
The study revealed that black women overall drink less alcohol than white women, with 45% of black women indicating they never drink alcohol. However, those who never drank were more likely to develop breast cancer compared with light drinkers, though the researchers are unsure of why. Prior studies showed comorbidities such as diabetes, which may prevent them from drinking alcohol.
“In the future, it may be worthwhile to better characterize women who identify as ‘never drinkers’ to understand reasons for abstaining from alcohol,” says Williams.
The researchers underscored that the study is important, as alcohol consumption can be changed or addressed.
“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,” says Troester. “However, alcohol drinking can be moderated if a woman wants to decrease her risk. Most studies show that risk is only significantly increased if women drink more than one drink per day. Women should talk to their doctors about whether these findings may help them reduce their risk of breast cancer.”
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.