Purpose: Obesity is a leading modifiable contributor to breast cancer mortality due to its association with increased recurrence and decreased overall survival rate. Obesity stimulates cancer progression through chronic, low-grade inflammation in white adipose tissue, leading to accumulation of adipose tissue macrophages (ATMs), in particular, the pro-inflammatory M1 phenotype macrophage. Exercise has been shown to reduce M1 ATMs and increase the more anti-inflammatory M2 ATMs in obese adults. The purpose of this study was to determine whether a 16-week exercise intervention would positively alter ATM phenotype in obese postmenopausal breast cancer survivors.
Methods: Twenty obese postmenopausal breast cancer survivors were randomized to a 16-week aerobic and resistance exercise (EX) intervention or delayed intervention control (CON). The EX group participated in 16 weeks of supervised exercise sessions 3 times/week. Participants provided fasting blood, dual-energy X-ray absorptiometry (DXA), and superficial subcutaneous abdominal adipose tissue biopsies at baseline and following the 16-week study period.
Results: EX participants experienced significant improvements in body composition, cardiometabolic biomarkers, and systemic inflammation (all p < 0.03 vs. CON). Adipose tissue from EX participants showed a significant decrease in ATM M1 (p < 0.001), an increase in ATM M2 (p < 0.001), increased adipose tissue secretion of anti-inflammatory cytokines such as adiponectin, and decreased secretion of the pro-inflammatory cytokines IL-6 and TNF- α (all p < 0.055).
Conclusions: A 16-week aerobic and resistance exercise intervention attenuates adipose tissue inflammation in obese postmenopausal breast cancer survivors. Future large randomized trials are warranted to investigate the impact of exercise-induced reductions in adipose tissue inflammation and breast cancer recurrence.
Keywords: Adipose tissue; Body composition; Macrophages; Obesity.