Central Obesity, Adiposity Tied to Mortality in Black Breast Cancer Patients

By Lisa Rapaport

June 14, 2021

(Reuters Health) - Black breast cancer patients with higher adiposity, particularly based on waist-to-hip ratio, are at increased risk of death from breast cancer and all causes, a U.S. study suggests.

Researchers examined data on 1,891 Black women diagnosed with breast cancer at a mean age of 54.4 years. After a median follow-up period of 5.9 years, a total of 286 women died, including 175 fatalities (61.2%) from breast cancer.

All the women in the study had measurements of adiposity, including body mass index, waist-to-hip ratio, and waist circumference, as well as percentage body fat and fat mass index, taken at about 10 months after diagnosis. More than half of participants had obesity (56.1%) and central obesity (68.3%).

Women in the highest quartile for waist-to-hip ratio were significantly more likely to die of all causes (HR 1.61) or from breast cancer (HR 1.68) during follow-up. Women in the highest quartile for waist circumference were also significantly more likely to die of all causes (HR 1.74) and breast cancer (HR 1.64), as were women in the top quartile for percent body fat (HR 1.53 and 1.81, respectively) and fat mass index (HR 1.57 and 1.74, respectively).

"Higher adiposity has been shown to reduce breast cancer survival and this could be due to several interrelated physiological pathways, including changes in hormonal and metabolic biomarkers as well as systemic and tissue-level inflammation," said lead study author Dr. Elisa Bandera, professor and chief of cancer epidemiology and health outcomes at the Rutgers Cancer Institute of New Jersey and Robert Wood Johnson Medical School in New Brunswick, New Jersey.

"Central obesity, which can be measured by a high waist circumference or waist-to-hip ratio, is particularly relevant as a proxy of intra-abdominal fat, which is more strongly associated to insulin resistance and metabolic syndrome, and these can increase progression," Dr. Bandera said by email.

The risk increase for both all-cause and breast cancer-specific mortality was smaller for women in the highest quartile for body mass index (HR 1.26 and 1.33, respectively), researchers report in JAMA Oncology.

In analyses stratified by estrogen receptor status, menopausal status, and age, a higher waist-to-hip ratio was associated with all-cause mortality in women with estrogen-receptor negative tumors (HR 2.24), women who were postmenopausal (HR 2.15), and those 60 years or older at diagnosis (HR per 0.10-U increase, 1.76).

One limitation of the study is that researchers lacked data to assess the risk by tumor subtype or to examine shifts in weight or body composition over time, the study team notes.

Even so, the findings suggest that BMI alone is not a great marker of mortality risk in Black women with breast cancer, said Dr. Erica Warner, an assistant professor at Harvard Medical School and an assistant investigator at Massachusetts General Hospital in Boston.

"Clinical assessments should go beyond height and weight to also measure waist and hip circumference and potentially body composition," Warner, who wasn't involved in the study, said by email. "Patients with central adiposity could be counseled on the implications this finding, offered strategies to reduce adiposity, and referred for supportive services such as to a nutritionist."

SOURCE: https://bit.ly/3zeCFR7 JAMA Oncology, online June 4, 2021.