Breast Cancer Coverage from Every Angle

Body Mass Index and Breast Cancer Outcomes by Racial Ancestry

By: Lauren Harrison, MS
Posted: Friday, July 9, 2021

Among women with high-risk, HER2-negative breast cancer, higher body mass index (BMI) was associated with worse outcomes in patients of African ancestry, but not in those of European ancestry, based on a retrospective analysis from the E5103 trial. Tarah Jean Ballinger, MD, of the Indiana University School of Medicine, presented these findings on behalf of her colleagues during the 2021 American Society of Clinical Oncology (ASCO) Annual Meeting (Abstract 1010).

“Determination of the optimal populations for weight loss interventions will advance precision medicine efforts to impact racial disparities and outcomes in early-stage breast cancer,” concluded the authors.

Researchers utilized data from the adjuvant E5103 study, which enrolled patients with high-risk HER2-negative breast cancer. Patients received doxorubicin/cyclophosphamide for four cycles, followed by weekly paclitaxel for 12 weeks with or without bevacizumab. The team determined the genetic ancestry for 2,854 patients with available germline DNA and then correlated these data with patients’ BMI and outcomes.

Within the data set, 13.4% of patients were genetically classified as African American and 86.6% were categorized as European American. A BMI higher than 40 kg/m2 (class II obesity) was associated with worse disease-free and overall survival in African American patients (disease-free survival hazard ratio = 1.98, overall survival hazard ratio = 2.07). However, this was not the case among European American patients, as this population saw almost no difference in disease-free survival (hazard ratio = 0.97) or overall survival (hazard ratio = 1.28) with a BMI higher than 40 kg/m2. BMI was associated with worse outcomes only in African American patients with estrogen receptor–positive breast cancer, but not in those with triple-negative breast cancer. The proportion of African ancestry was associated with higher BMI and worse outcomes within the total population; however, within the African American population, there was no effect of the proportion of African ancestry on BMI and disease-free survival (hazard ratio = 0.36) or overall survival (hazard ratio = 0.38).

Disclosure: For a full list of authors’ disclosures, visit

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