Abstract C122: Ethnicity as a moderator of the effects of aerobic and resistance exercise on metabolic syndrome in breast cancer survivors
Authors: Dieli-Conwright Christina M. , Sweeney Frank C. , Courneya Kerry S. , Tripathy Debu , Sami Nathalie , Lee Kyuwan , Buchanan Thomas A. , Spicer Darcy , Bernstein Leslie , Mortimer Joanne E. , Demark-Wahnefried Wendy 
Published: August 2020

Background and Purpose: Metabolic syndrome (MSY) is associated with increased risk of cardiovascular disease, type 2 diabetes, and recurrence in breast cancer survivors (BCS). MSY is 1.5 times more common in Hispanic compared to non-Hispanic women. Hispanic women in the United States are more likely to be obese and physically inactive than matched non-Hispanic counterparts, raising risk for developing MSY. Exercise mitigates MSY in BCS; however, few studies have focused on minorities. The purpose of this secondary analysis was to examine ethnicity as a moderator of the effects of a 16-week combined aerobic and resistance clinical exercise intervention on MSY and related biomarkers in BCS.

Experimental Design: Sedentary, overweight or obese (BMI&gt;25.0 kg/m2) BCS (Stage I-III; n=100) were randomized to exercise (n=50) or usual care (n=50). The exercise intervention promoted supervised, progressive moderate-vigorous (65-85% heart rate maximum) aerobic and resistance exercise thrice weekly for 16 weeks. Aerobic exercise included cycling, walking, or jogging at 65-85% maximum heart rate. Resistance exercise was performed in circuit-fashion with 3 sets of 10-15 repetitions including upper and lower body exercises at 65-70% 1-repetition maximum. MSY variables (blood pressure, waist circumference, triglycerides, glucose, and high-density lipoprotein-cholesterol) and related biomarkers (insulin, insulin resistance HOMA-IR, C-reactive protein [CRP]) were measured at baseline and post-intervention (4 months). Differences in mean changes for outcomes by ethnicity were evaluated using linear mixed-models to assess effect modification.

Summary of Results: Fifty-seven Hispanic BCS and 43 non-Hispanic BCS with an average age of 53.5±10.4 years and BMI of 33.5±5.5 kg/m2 were included. Hispanic BCS were younger, of greater adiposity, had higher-stage cancers, and had worse metabolic profiles at baseline compared to non-Hispanic BCS (p&lt;0.001). Ethnicity was found to moderate the effects of exercise training on triglycerides (mean difference, -36.4; 95% confidence interval (95% CI), -62.1-18.3; p=0.04) and glucose (mean difference, -8.6; 95% CI, -18.7-3.1; p=0.05) with Hispanic BCS exhibiting larger improvements than non-Hispanic BCS. Ethnicity moderated the effect of exercise on insulin (P for interaction=0.09), HOMA-IR (P for interaction=0.06), and CRP (P for interaction=0.05).

Conclusions: Hispanic, as compared to non-Hispanic, BCS have poorer metabolic profiles, but may achieve better outcomes from exercise. To our knowledge, this is the first study to explore racial/ethnic disparities in MSY between Hispanic and non-Hispanic BCS and document differential response to exercise. Clinical exercise interventions may attenuate ethnic health disparities in BCS. Future trials should aim for diversity.

Citation Format: Christina M. Dieli-Conwright, Frank C. Sweeney, Kerry S. Courneya, Debu Tripathy, Nathalie Sami, Kyuwan Lee, Thomas A. Buchanan, Darcy Spicer, Leslie Bernstein, Joanne E. Mortimer, Wendy Demark-Wahnefried. Ethnicity as a moderator of the effects of aerobic and resistance exercise on metabolic syndrome in breast cancer survivors [abstract]. In: Proceedings of the Eleventh AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2018 Nov 2-5; New Orleans, LA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl):Abstract nr C122.