Association Between Systemic Inflammation And Skeletal Muscle Mass Following Exercise In Breast Cancer Survivors

Abstract

INTRODUCTION: Reductions in skeletal muscle mass contribute to reduced physical function and poorer prognosis among breast cancer survivors (BCS). Elevated pro-inflammatory markers stimulate catabolic pathways in skeletal muscle, and have been associated with muscle loss in overweight individuals and older adults. This evidence suggests that elevated pro-inflammatory markers such as IL-6, TNF-alpha , and C-reactive protein (CRP) may explain subsequent muscle loss in BCS. While we previously found exercise reduces inflammation and increases skeletal muscle mass in overweight or obese BCS, an associative investigation is warranted. PURPOSE: The purpose of this secondary analysis was to determine whether associations between post-exercise inflammatory markers and skeletal muscle mass exist among overweight/obese BCS. METHODS: Sedentary, overweight/obese BCS (BMI ≥ 25 kg/m2; Stages I-III) were randomized to exercise (EX; n=50) and control (CON; n=50) groups. EX participated in a supervised 16-week moderate-vigorous intensity aerobic and resistance exercise intervention. CON was asked to maintain current levels of activity. Appendicular Skeletal Muscle Index (ASMI), calculated as ∑extremity lean mass (kg)/ height (m2), was obtained from a whole-body scan using Dual Energy X-Ray Absorptiometry. CRP, IL-6, and TNF-∝ were measured using enzyme-linked immunosorbent assays from fasting blood samples. Pearson’s correlations assessed associations between post-exercise ASMI and inflammatory biomarkers. RESULTS: On average, BCS were 53.5±10.4 years old, postmenopausal (60%), and Hispanic (55%) with a BMI of 33.5±5.5 kg/m2. Post-intervention, EX experienced an increase in ASMI (8.3%; p=0.001), and reductions in CRP (-47.8%; p=0.001) IL-6 (-73.6%; p=0.001) and TNF-∝ (-25.1%; p=0.001). No significant changes were seen in CON (p>0.01). There were significant correlations between ASMI and IL-6 (r=-0.78; p=0.02), CRP (r=-0.91; p=0.01), and TNF-alpha (r=-0.82; p=0.03). CONCLUSIONS: This secondary analysis provides preliminarily evidence to support the relation between changes in skeletal muscle mass and inflammation among BCS, and supports the implementation of exercise to maintain muscle mass during survivorship.