Physical Function Appears Stable Across 24 Weeks Of Treatment For Advanced Prostate Cancer

Cross-sectional studies indicate that men with metastatic prostate cancer (PC) using androgen receptor signaling inhibitors (ARSI) have lower physical function (PF). However, the rate of change in PF remains unclear. PURPOSE: This observational pilot study longitudinally examined objectively measured PF in men with advanced PC initiating ARSI treatment. Additionally, changes in grip strength, muscular power, balance, and body composition were evaluated. METHODS: Study participants (n = 13, 73 ± 8 y, 29.2 ± 4.3 kg/m2 BMI) completed testing at baseline and 24-weeks. The majority (77%) of men were diagnosed with castration-sensitive metastatic PC. The primary outcome was PF and was assessed using a composite of short physical performance battery [SPPB], timed up and go [TUG], and 400 m walk. Secondary outcomes included grip strength (handgrip dynamometry), peak and mean power (GymAware sit-to-stand test), body composition (dual energy X-ray absorptiometry), and balance (Sensory Organization Test). Mean differences (MD) were calculated as 24-week - baseline. Effect sizes are reported as Cohen’s D. RESULTS: From baseline to 24 weeks of ARSI, no changes in PF where observed in the 400 m walk [MD: +1.8 s; 95% CI (-13.3, -16.8); p = 0.822, d = 0.05], SPPB [+0.3 points; (-0.03, 0.8); p = 0.363, d = 0.27] or TUG [+0.3 s; (-0.6, 1.2); p = 0.512, d = 0.18]. For the secondary outcomes, no differences were observed for muscle function when assessing grip strength [-0.1 kg; (-2.3, 1.9); p = 0.874, d = 0.03] or mean power [-13 W; (-74, 48); p = 0.682, d = 0.13]. Peak power decreased by -11.8% [-102 W; (-228, 23); p = 0.134, d = 0.50] and lean mass by -2.8% [-1.6 kg; (-4.2, 1.1); p = 0.271, d = 0.31) with a 4.1% increase in balance [+3.0 pt; (-2.1, 8.1); p = 0.274, d = 0.29] that yielded small to moderate effect sizes but none reached statistical significance. CONCLUSIONS: Contrary to prior cross-sectional studies, these preliminary results suggest that 24 weeks of ARSI may not adversely affect objectively measured PF, nor any of our secondary outcomes associated with PF. As such, PF may be more stable during ARSI for hormone-sensitive PC than previously thought. However, the current sample size and possible learning effects in some tasks warrants caution and requires further investigation. This work was supported by the National Cancer Institute. Lauren C. Bates-Fraser is supported by the National Cancer Institute's National Research Service Award sponsored by the Lineberger Comprehensive Cancer Center at the University of North Carolina (T32 CA116339).