Moderators of resistance-based exercise programs' effect on sarcopenia-related measures in men with prostate cancer previously or currently undergoing androgen deprivation therapy: An individual patient data meta-analysis

Introduction: Older men with prostate cancer are commonly affected by reductions in lean mass and physical function following androgen deprivation therapy (ADT). Resistance-based exercise programs are critical to counteract the musculoskeletal toxicities derived from prostate cancer treatment and aging. However, there is significant variability in the effects of exercise interventions. Examining demographic and clinical moderators of exercise effects in this patient group can assist in identifying which subgroups of patients benefit most. Therefore, we examined the effects and moderators of resistance-based exercise programs on sarcopenia-related outcomes that included lean mass, skeletal muscle index, physical function, and muscle strength in older men with prostate cancer. Materials and Methods: Data were retrieved from the Predicting OptimaL cAncer RehabIlitation and Supportive care (POLARIS) consortium. For the present study, we included data from trials that examined the effects of supervised resistance-based exercise interventions on lean mass outcomes, muscle strength, and physical function in patients with prostate cancer previously or currently treated with ADT. Linear mixed models were undertaken to analyse the effects of resistance-based exercise programs considering the clustering of patients within studies. Effects were evaluated by regressing the study group on the post-intervention value of the outcome adjusted for the baseline value, while potential moderators were examined by adding the moderator and its interaction term into the regression model. Results: A total of 560 patients with prostate cancer (age: 69.5 ± 7.8 yrs.; body mass index: 28.6 ± 4.0 kg.m⁻²) previously or currently treated with ADT were included. Resistance-based exercise programs resulted in significant effects on whole-body and appendicular lean mass and the skeletal muscle index (P < 0.05), with improvements observed across different characteristics. Improvements were also observed in 400-m walk and 6-m backwards tandem walk (P < 0.05), with patients presenting with lower baseline levels deriving greater exercise effects on 400-m walk (−19.4 s, 95% confidence interval [CI]: −36.6 to −2.3) and 6-m backwards tandem walk tests (−3.0 s, 95% CI: −5.7 to −0.3). For relative muscle strength, significant exercise effects were observed, with greater effects in younger patients (0.35 kg.kg⁻¹, 95% CI: 0.22 to 0.48). Discussion: Resistance-based exercise programs effectively improve well-known markers of sarcopenia in men with prostate cancer, with specific subgroups of patients, such as those younger and presenting with lower baseline levels of physical function, deriving greater effects on muscle strength and physical function, respectively.