Purpose: We aimed to investigate the association of body composition with survival and efficacy of first-line treatment in patients with castration-resistant prostate cancer (CRPC).
Materials and Methods: Records of CRPC patients who were treated with docetaxel or androgen receptor signaling inhibitors (ARSi) between 2005 and 2018 were reviewed. Skeletal muscle index (SMI), visceral fat index, and subcutaneous fat index were evaluated using pretreatment computed tomography images.
Results: Of the 230 eligible patients, 144 patients received docetaxel and 86 received ARSi as the first-line treatment for CRPC. SMIhi (based on median value) group had higher PSA progression-free survival (median 13.5 vs. 8.3 months, p=0.030), radiologic progression-free survival (14.9 vs. 9.1 months; p<0.001), and overall survival (24.1 vs. 16.9 months, p=0.015) compared than SMIlo group. In multivariable analysis, SMI was independently associated with risk of overall death (HR=0.61, p=0.004).
In docetaxel-treated patients, PSA progression-free survival (13.5 vs. 5.9 months, p=0.016) and radiologic progression-free survival (14.6 vs. 6.7 months, p<0.001) was higher in SMIhi than SMIlo group. However, PSA progression-free survival (14.5 vs. 14.0 months, p=0.566) and radiologic progression-free survival (15.9 vs. 15.6 months, p=0.527) was similar between two groups in ARSi-treated patients.
Conclusions: Low skeletal muscle mass may be associated with increased risks of disease progression and mortality in patients with CRPC. However, the impact of SMI on progression is limited in patients treated with docetaxel. These results suggest that SMI may be a potential treatment selection biomarker in CRPC. Further prospective studies are warranted.
