Association of Diet Quality and Physical Activity on Obesity-Related Cancer Risk and Mortality in Black Women: Results from the Women’s Health Initiative

BACKGROUND:

Obesity-related cancers disproportionately affect the Black community. We assessed the relationship between dietquality, physical activity and their combined effect on obesity-related cancer risk and mortality in Black women enrolled in the Women’sHealth Initiative (WHI).

METHODS:

Data from postmenopausal (50-79 years), Black women enrolled in WHI clinical trials or observational studies were analyzed. Exposure variables included baseline physical activity (MET-hours/week of Moderate-to-Vigorous Physical Activity (MVPA)) and diet quality (Healthy Eating Index (HEI)-2015). Outcomes included adjudicated obesity-related cancer incidence and mortality. Cox proportional hazard models were used to evaluate the association between MVPA and HEI-2015 and obesity-related cancer risk and mortality.

RESULTS:

The analytical sample included 9,886 Black women, with a baseline mean BMI of 31.1 kg/m2 (sd 6.8); mean HEI-2015 score of 63.2 (sd 11.0, possible range 0 to 100); and mean MVPA of 5.0 (sd 9.4) MET-hours/wk. Over an average of 13 years of follow-up, 950 (9.6%) obesity-related cancer cases were observed, with 313 (32.9 %) resulting in death. Physical activity (HR 1.05, 95% CI: 0.86, 1.30), diet quality (HR: 0.99, 95% CI 0.92, 1.08), and their combination (HR 1.05, 96% CI: 0.85, 1.29) were not associated with risk for any or site-specific obesity-related cancers. Similarly, these health behaviors had no association with mortality.

CONCLUSION:

Diet quality, physical activity and their combined effect, as measured, were not associated with obesity-related cancerrisk and mortality in Black women enrolled in WHI.

IMPACT:

Other social, behavioral and biological factors may contribute to racial disparities observed in obesity-related cancer rates.