The Weight of Race on Cancer

Being underweight or way overweight can affect a person’s ability to beat breast cancer. The role weight plays in who wins and who loses against this cancer varies among women.

A woman's race apparently influences how weight affects her long-term odds against breast cancer. 

Being at the extremes on the weight spectrum – underweight, extremely overweight, or having lots of abdominal fat – was associated with the worst health outcomes.

Exercise regularly to reach a healthy weight.

This research was conducted by Kaiser Permanente Northern California Division of Research in Oakland, Calif.

"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 Marilyn L. Kwan, PhD, a Kaiser research scientist in a press release.

Dr. Kwan and her team examined data in the California Breast Cancer Survivorship Consortium. Weight and body mass index (BMI) information was available for 11,351 women, including 6,044 non-Latina whites, 1,886 African-Americans, 1,451 Asian-Americans, 1,864 Latinas and 106 others.

Compared to women with normal weight, here’s what researchers found for non-Latina white women:

• Women who were underweight (a BMI of less than 18.5) at the time of their diagnosis had a 47 percent greater risk of dying from any cause (overall mortality) including breast cancer.
• Morbidly obese women (BMI of more than 40) had a 43 percent increased risk of overall mortality.
• Women with the highest waist-to-hip ratios – a measure of abdominal fat – had a 30 percent increased risk of overall mortality and a 36 percent greater risk of dying from breast cancer compared with women with the smallest waist-to-hip ratios.

On closer examination, these rates differed according to a woman’s race and ethnicity.

According to Dr. Kwan, “African-American women and Asian-American women with larger waist-to-hip ratios had poorer survival, an observation not seen in non-Latina white women and Latina women."

Being extremely obese was the only heightened mortality risk factor for Latina women. While the study supports earlier findings regarding weight and mortality in breast cancer patients, Dr. Kwan says these trends are not true for all women.

The authors concluded, “Obesity and body fat distribution around breast cancer diagnosis appear to have differential effects on survival depending on race/ethnicity.”

Adam Brufsky, MD, PhD, professor of medicine at the University of Pittsburgh School of Medicine, told dailyRx News, "This shows us that healthy weight maintenance is even more important in underserved populations."

Findings from this study, funded by the California Breast Cancer Research Program, were presented at the Fifth AACR Conference on The Science of Cancer Health Disparities.

All research is considered preliminary before it’s published in a peer-reviewed journal.