Breast Cancer Survival Disparities: Need to Address Obesity

Sharon Worcester

December 10, 2020

The poorer survival rates in Black women compared with White women with breast cancer could be explained to some extent by the finding of much higher rates of obesity, obesity-related comorbidities, and overall comorbidities in Black women, say researchers reporting a retrospective chart review from their clinic.

Kirsten A. Nyrop, PhD, deputy director for research for the Geriatric Oncology Program at the University of North Carolina, Chapel Hill, and colleagues analyzed medical charts for 144 Black women and 404 White women with early breast cancer.

Obesity rates were nearly double among Black women, at 62% vs 32%.

In addition, significantly more Black women had two or more total comorbidities (62% vs 47%), two or more obesity-related comorbidities (33% vs 10%), hypertension (60% vs 32%), type 2 diabetes (23% vs 6%), and hypercholesterolemia or hyperlipidemia (28% vs 18%).

These racial disparities persisted after adjusting for age and body mass index, both independent predictors of chronic diseases.

The difference in obesity and comorbidity did not translate to differences in treatment decisions such as surgery type, chemotherapy regimen, radiation, or endocrine treatment, the researchers note.

The findings were published online December 7 in the journal Cancer.

They underscore the likely role of obesity and related complications in the racial disparities seen in breast cancer survival outcomes, the authors conclude.

Experts writing in an accompanying editorial agree, while emphasizing the well documented differences in survival.

Compared with White women with breast cancer, Black women with breast cancer have a 42% higher mortality rate, and a greater likelihood of dying from breast cancer regardless of their age at diagnosis, note Caitlin E. Taylor, MD, and Jane Lowe Meisel, MD, of Emory University, Atlanta, Georgia.

"Although it is clear that the causes of such disparities are complex and multifactorial, questions remain regarding to what extent patient comorbidities, and specifically obesity, may be playing a role," they write.

The obesity- and comorbidity-related disparities identified by Nyrop et al "undoubtedly contribute to the overall disparities noted in breast cancer outcomes among Black women," they add.

Takeaway Messages

Nyrop and colleagues say their findings have two important takeaway messages:

1) It is important to manage comorbidities in women with newly diagnosed early breast cancer to reduce the risk of mortality from competing causes, and

2) Excess weight at diagnosis and weight gain after primary treatment increase the risk of obesity-related disease that can affect survival, and patients should be educated about the association.

Such conversations should be "patient-centered and culturally appropriate," they note.

In their editorial, Taylor and Meisel agree with the authors' conclusions.  "Given the higher prevalence of obesity and related comorbidities among Black patients, addressing these issues must become an integral part of early breast cancer management to prolong overall survival and continue improving outcomes for these women."

In fact, addressing comorbidities early in breast cancer management is important for patients of all racial and ethnic backgrounds, the editorialists add, concluding that the role of obesity as "a critical player underlying breast cancer mortality" is increasingly clear, and that its management is crucial for improved outcomes and quality of life.

This study was supported by the Breast Cancer Research Foundation, the National Cancer Institute's Breast Cancer Specialized Program of Research Excellence, and the University of North Carolina Lineberger Comprehensive Cancer Center/University Cancer Research Fund. The study authors reported have disclosed no relevant financial relationships. Meisel has received research support from Pfizer, Eli Lilly, and Seattle Genetics and has served as a paid advisor for Pfizer, PUMA, Novartis, and Clovis Oncology. Taylor has disclosed no relevant financial relationships.

Cancer. Published online December 7, 2020. Abstract, Editorial

Sharon Worcester is a reporter for MDedge News, part of the Medscape Professional Network.

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