The link between obesity and an increased risk for breast cancer may vary by ethnicity and race, suggest study results presented Monday at a meeting of the American Association for Cancer Research, in San Diego, by Marilyn L. Kwan, Ph.D., a research scientist in the Kaiser Permanente Northern California Division of Research. The study has not been published yet, therefore details have not been released entirely.
Previous reports link breast cancer mortality and ethnicity; however, until now, experts were not clear on why the disparity exists.
“The majority of studies among primarily non-Latina white populations on obesity before a diagnosis of breast cancer have found that increased weight is associated with poorer survival, yet few studies have examined if this association holds true within the major minority groups of African-Americans, Latinas and Asians and whether differences in obesity might explain racial/ethnic differences in survival,” said Kwan.
Breast cancer, obesity and ethnic group study
For the research, Kwan and her team analyzed data from more than 12,000 female breast cancer patients. The body mass index (BMI) was available for more than 11,000 women. Approximately 6,000 of the study participants were non-Latina whites, 1,886 were African-American, 1,451 were Asian-Americans, 1,864 were Latinas and 106 were identified as “others.”
What the researchers found was that being underweight was also associated with a higher risk for a breast cancer diagnosis, as was being overweight.
Women classified as underweight had a 47 percent increased risk of mortality when compared to women of normal weight, and women in the study classified as obese had a 43 percent increased mortality risk.
Regardless of total weight, high levels of abdominal fat were associated with a 30 percent increased risk of overall mortality as well as a 36 percent increased mortality related to a breast cancer diagnosis.
Ethnic and racial disparities were found during the study, said Kwan, who indicated non-Hispanic white women had a higher risk of breast cancer mortality if they were underweight or overweight at the time of diagnosis. This was not true for any of the other ethnic groups in the study; however, African-Americans and Asian-Americans with larger hip-to-waist ratios had poorer rates of survival compared to non-Hispanic whites and Latinas.
Among Latinas specifically, an increased risk of mortality from breast cancer was only seen among the morbidly obese, a finding Kwan says supports the push to Hispanics in the U.S. to maintain a healthy lifestyle and active routine.