Two new studies find that obesity can increase the risk of particular types of breast cancer in African-American and Hispanic women, especially if they are postmenopausal.

One of the studies analyzed 3,200 Hispanic women, and found that those who were overweight or obese — as well as postmenopausal — had a higher risk for estrogen receptor-negative and progesterone receptor-positive breast tumors. Previous studies on obesity’s effect on Hispanic women's risk for breast cancer had been small and inconsistent. For example, a study published in 2010 found that there was no link between breast cancer and obesity among Mexican-American women.

“We’ve known this for a long time for white women, but now we are seeing this also in Hispanic women,” said Esther John, a senior research scientist at the Cancer Prevention Institute of California and author of the study, in a press release. In addition, she added that “breast cancer appears to have different risk factors in younger versus older women, but by far, breast cancer is more common among postmenopausal women.”

The second study was led by epidemiologist Dr. Elisa V. Bandera of the Rutgers Cancer Institute of New Jersey. Bandera and her research team analyzed obesity’s link to different hormone-receptor types among some 15,000 African-American women. They found that being overweight was associated with a 31 percent increase of ER positive tumors in postmenopausal African-American women.

Breast cancer isn’t a single disease; in fact, there are many different ways to classify it. As a result, certain people are more likely to be affected by different subtypes; and each subtype has its own risk factors. “We know that breast cancer has several subtypes and there is growing evidence that these subtypes have different risk factors,” Bandera said in the press release. “The distribution of these subtypes and risk factors are different for African-Americans and Hispanics compared to white women.”

According to the Breast Cancer Fund, the “diagnostic and prognostic descriptions of subtypes of breast cancer have become increasingly sophisticated over the past decades.” There are three main groups that help doctors define breast cancer subtypes: understanding the site of the tumor’s origin (ductal or lobular cancer); whether the tumor is contained within the walls of the ducts or lobes; and the “reproductive status” of the women, or whether they’re pre-menopausal or post-menopausal.

Though more research will be needed to fully grasp how obesity may increase the risk of cancer, it’s enough for now to know that eating healthy and maintaining a normal weight is one of your best prevention strategies for pretty much any chronic disease out there, including cancer. According to the National Cancer Institute (NCI), other research has discovered links between obesity and cancers of the esophagus, pancreas, endometrium, kidney, thyroid, and gallbladder, among others. One 2007 study out of the NCI estimated that around 34,000 new cases of cancer in males (four percent) and 50,500 in women (seven percent) could be attributed to obesity.

“This has huge implications for not just Hispanics but all women,” John said. “We cannot change genetics or family history, but we can do something about obesity. You can eat less, choose healthier foods and do more physical activity… And it’s important for not just lowering breast cancer risk but for many other diseases.”

Sources: John E, Sangaramoorthy M, Hines L, Stern M, Baumgartner K, Giuliano A. “Overall and abdominal adiposity and premenopausal breast cancer risk among Hispanic women: The Breast Cancer Health Disparities Study.” Cancer Epidemiology, Biomarkers & Prevention, 2014.

John E, Sangaramoorthy M, Hines L, Stern M, Baumgartner K, Giuliano A. “Body size throughout adult life influences postmenopausal breast cancer risk among Hispanic women: The Breast Cancer Health Disparities Study.” Cancer Epidemiology, Biomarkers & Prevention, 2014.