Association between Diet Quality and Obesity-Related Cancer in Postmenopausal Hispanic Women: Results from the Women’s Health Initiative (WHI)

Abstract

The prevalence of obesity is higher in Hispanic women than for Non-Hispanic Whites (NHW) with rates of 45% and 33%, respectively; yet, Hispanic women have lower incidence of most obesity-related cancers as compared to NHW. Little is known about the role of diet, a modifiable risk factor, and obesity-related cancer risk in this population. Previous work in the Women’s Health Initiative (WHI) found that post-menopausal Hispanic women with higher adherence to the American Cancer Society (ACS) guidelines for diet and physical activity demonstrated lower cancer incidence. More specifically, Hispanic women with the highest adherence to ACS guidelines had a 47% risk reduction for any incident cancer. These data warrant further investigation of the relationship between diet and cancer risk in post-menopausal Hispanic women. The purpose of this project was to evaluate the association between diet quality, as measured by alternate Mediterranean Score (aMED), the Healthy Eating Index-2015 (HEI-2015), the Dietary Inflammatory Index (DII) and Mexican Diet (MexD) score, and incidence of obesity-related cancers among Hispanic postmenopausal women participating in the WHI. Baseline dietary intake of WHI clinical trial and observational study Hispanic women (N= 5,482), estimated from Food Frequency Questionnaires (FFQ), were scored for dietary quality. Scores can range from 0 to 9 for the aMED score, 0 to 100 for the HEI-2015, -8.87 to 7.98 for the DII, and from 0 to 12 for the MexD score. Scores were divided into quartiles of increasing score. Cox proportional hazard analyses adjusted for age, body mass index (BMI), smoking, alcohol, neighborhood socioeconomic status (NSES), diabetes, physical activity, and clinical trial arm(s) were performed to evaluate diet quality scores and obesity-related cancer risk. Among Hispanic postmenopausal women, there were 399 incident cases of obesity-related cancer over a period of 12 years. Congruent with national statistics, the most prevalent cancer types were breast (n= 207) and colorectal (n= 64 cancers). Mean diet quality scores were as follows; for aMED 3.5 ± 1.6, 56 ± 11.6 for HEI-2015, for DII -0.46 ± 1.9, and MexD 5.7 ± 1.9. Hazard Ratio (HR) for any cancer were 1.22 (95% CI= 0.92, 1.62) for aMED, 0.97 (95% CI= 0.75, 1,26) for HEI-2015, 0.96 (95% CI= 0.74, 1.24) for DII and 0.91 (95% CI= 0.71, 1.18) for MexD scores. For obesity-related cancer HR were 0.94 (95% CI= 0.66, 1.34) for aMED scores, 0.91 (95% CI= 0.66, 1.25) for the HEI-2015, 1.18 (0.86-1.62) for DII, and 0.97 (95% CI= 0.70, 1.33). These results suggest that higher scores representative of a higher diet quality for aMED, HEI-2015, and MexD, and lower DII scores, are not associated with total cancer and obesity-related cancer risk in postmenopausal Hispanic women enrolled in WHI.