Trends in bone health agents use and skeletal events in metastatic castration-resistant prostate cancer in The Netherlands

Bone healt agents (BHAs) prevent symptomatic skeletal events (SSEs) in bone-metastatic castration-resistant prostate cancer (mCRPC). A study in the Netherlands evaluated contemporary BHA utilization and SSE incidence (2016-2021; Dutch CAPRI-3 registry) compared with a historical cohort (2010-2015; Dutch CAPRI-2 registry). CAPRI-3 and CAPRI-2 comprised 2115 and 1923 CRPC patients with bone metastases, respectively. Clinical evolution and SSE outrcomes were analyzed in 1792 patients receiving life-prolonging drugs (LPDs), categorized by BHA timing relative to the first LPD: no BHA, early BHA (≤ 4 weeks), of late BHA. Compared to the historical cohort, patients in the 2016-2012 cohort were older (75 versus 73 years), frailer (Charlson Comorbidity Index≥ 5: 44% versus 13%), and received LPDs in metastatic castration-sensitive setting more frequently (35% versus 0%). BHA utilization dropped from 60% to 28%, with only 8% receiving guideline-recommended timing of BHA initiation. However, the overall SSE incidence declined from 0.26 to 0.21 events per patient-year between cohorts. Early BHA initiation was predominantly reserved for high-risk disease; this group experienced the highest SSE density (0.29) and shortest median SSE-free survival (8.7 versus 14.6 months; p<0.001) compared with the group without BHA. The authors conclude that, as the mCRPC population becomes older and more pretreated, guideline-recommended BHA timing remains limited. The high SSE density in high-risk patients underscores the need to identify those patients most likely to benefit from early bone protection.