The clinical relevance of adiposity when assessing muscle health in men treated with androgen deprivation for prostate cancer

Background: Androgen deprivation therapy (ADT) for prostate cancer (PCa) may prospectively decrease absolute lean mass (LM) and increase absolute fat mass (FM). Given that estimates of LM by dual-energy X-ray absorptiometry may be overestimated in obese people, this study examined the influence of adiposity on muscle health in men treated with ADT for PCa. Methods: This cross-sectional study examined the influence of adiposity on total and appendicular LM (ALM), muscle cross-sectional (CSA), and muscle strength in 70 men treated with ADT [mean (standard deviation) age, 71 (6) years] for PCa compared with age-matched PCa (n = 52) and healthy controls (n = 70). Total body LM, FM and ALM, and 66% tibia and radius muscle CSA were quantified by dual-energy X-ray absorptiometry and peripheral quantitative computed tomography, respectively. ALM was further divided by height (m²) or body mass index, with muscle CSA expressed as a per cent of total limb CSA. Upper and lower body and back (three-repetition maximum and dynamometry) muscle strength were expressed per kilogram of body weight. Results: On average, ADT-treated men had 4.4–6.4 kg greater FM compared with controls (P ≤ 0.014) and there were no differences in total body or ALM. Total body per cent LM and ALM_BMI were 3.8–5.4% (P ≤ 0.001) and 7.8–9.4% (P ≤ 0.001) lower, respectively, in ADT-treated men compared with both controls. Percentage muscle CSA at both sites and muscle strength (except leg) were 3.0–6.0% (P ≤ 0.031) and 15–17% (P ≤ 0.010) lower, respectively, in ADT-treated men compared with both controls. Conclusions: The findings from this study indicate muscle mass, size, and strength are compromised in men treated with ADT after accounting for their increased adiposity or body size.