Diabetes risk reduction diet and mortality outcomes following breast cancer diagnosis in Black women.

Abstract

10622 Background: Black women continue to experience a ~40% higher breast cancer mortality rate than White women. Type II diabetes (T2D) management-related factors have received increasing attention as contributors to this disparity. Emerging evidence, largely derived from studies conducted among White women, suggests that adherence to the diabetes risk reduction diet (DRRD) may be associated with improved breast cancer outcomes. Despite Black women having more than twice the risk of developing T2D compared with White women, no studies to date have examined the association between the DRRD and mortality among Black breast cancer survivors. Methods: We conducted a cohort analysis of 1,732 Black breast cancer survivors from the Women’s Circle of Health Follow-Up Study. Participants’ prediagnostic intake of DRRD components was calculated from validated food frequency questionnaires that included: cereal fiber, coffee, nuts, whole fruits, polyunsaturated/saturated fat ratio, glycemic index, trans fats, sugar-sweetened beverages, and red/processed meat. Consumption levels for each component were scored 1-5, summed to form a DRRD adherence score (higher scores signify greater adherence), and further categorized into tertiles. Death outcomes and causes were ascertained via linkage to the New Jersey State Cancer Registry. Associations with mortality were evaluated using multivariable-adjusted Cox proportional hazards regression models. Results: After a median of 10.8 years of follow-up since diagnosis, 422 total deaths (213 breast cancer-related) were identified. The mean DRRD score was 26 (std 5.5). In the multivariable–adjusted model, women with higher scores had a 34% lower risk of breast cancer-specific mortality (top vs. bottom tertile HR = 0.66; 95% CI = 0.46-0.93; p = 0.02) and a 23% lower risk of overall mortality (HR = 0.77; 95% CI = 0.59-1.00; p = 0.05). The associations were consistent across diabetes and menopausal status, and also across household income subgroups. However, the risk reduction appeared more pronounced among women with early-stage disease (HR = 0.54; 95% CI = 0.34-0.88), luminal tumor subtypes (HR = 0.49; 95% CI = 0.28-0.87), those with a BMI ≥30 kg/m 2 (HR = 0.55; 95% CI = 0.34-0.88), and those in the lower half of the neighborhood socioeconomic status distribution (HR = 0.57; 95% CI = 0.35-0.93), compared with their respective counterparts. Conclusions: This study represents the first and largest investigation of DRRD adherence and breast cancer outcomes among Black women. Our findings suggest that greater DRRD adherence may offer a protective effect on both breast cancer-specific and overall mortality in Black women, a population facing the highest breast cancer mortality in the US. More broadly, these results, together with prior evidence, suggest that adhering to dietary patterns consistent with T2D prevention may be important for both White and Black breast cancer survivors.