BMI, physical activity, and breast cancer subtype in white, black, and Sea Island breast cancer survivors.

Higher BMI, lower rates of physical activity (PA), and hormone receptor-negative breast cancer (BC) subtype are associated with poorer BC treatment outcomes. We evaluated the prevalence of high BMI, low PA level, and BC subtype among survivors with white/European American (EA) and African American (AA) ancestry, as well as a distinct subset of AAs with Sea Island/Gullah ancestry (SI). We used the South Carolina Central Cancer Registry to identify 137 (42 EAs, 66 AAs, and 29 SIs) women diagnosed with BC and who were within 6-21 months of diagnosis. We employed linear and logistic regression to investigate associations between BMI, PA, and age at diagnosis by racial/ethnic group. Most participants (82%) were overweight/obese (P=0.46). BMI was highest in younger AAs (P=0.02). CDC PA guidelines (≥150min/week) were met by only 28% of participants. The frequency of estrogen receptor (ER)-negative BC subtype was lower in EAs and SIs than in AAs (P<0.05). This is the first study to identify differences in obesity and PA rates, and BC subtype in EAs, AAs, and SIs. BMI was higher, PA rates were lower, and frequency of ER-negative BC was higher in AAs as compared to EAs and SIs. This study highlights the need to promote lifestyle interventions among BC survivors, with the goal of reducing the likelihood of a BC recurrence. Integrating dietary and PA interventions into ongoing survivorship care is essential. Future research could evaluate potential differential immune responses linked to the frequency of triple negative BC in AAs.