Bone health practices in metastatic prostate cancer (mPCA).

Abstract

e17119 Background: Patients (pts) with mPCA and bone metastases (BM) are at risk for skeletal-related events (SREs), which include pathologic fracture, bone irradiation or surgery, spinal cord compression, and hypercalcemia. This study examined the evaluation, prevention, and treatment of osteopenia/-porosis (OP/P) and BM in pts with mPCA at the UCCC and affiliated sites. Methods: Pts diagnosed with mPCA and BM between 2011-2021 and treated with ADT were included. Demographic, clinical, treatment, and outcomes data were retrospectively collected. The primary endpoint was time from mPCA diagnosis to first SRE. Secondary endpoints included rates of DEXA scans, rates of vitamin D and calcium supplementation, and bone agent toxicity. The log-rank test was conducted to compare the primary endpoint by use of a bone strengthening agent. The Kruskal Wallis non-parametric test was used for continuous variables and Fisher’s exact test for categorical variables. Results: Of the 369 pts with mPCA, 247 (66.9%) were treated with a bone agent. Median age at metastatic diagnosis (mDx) was 69.6 years. Pts were predominately white (315, 85.4%) with hormone-sensitive mPCA (mHSPC) (327, 88.6%) at mDx. There were no significant differences in race, ethnicity, PSA, Gleason score, or time on ADT between patients who did and did not receive a bone agent. 222 pts (60.2%) were former or current smokers, 5 (1.4%) had pre-existing low testosterone ( < 150 ng/dL), 8 (2.2%) had prolonged glucocorticoid use (equivalent > 10 mg prednisone for 30 days), and 17 (4.6%) had known OP/P prior to mDx. 130 pts (35.3%) had a DEXA scan (27 pre-ADT, 103 post-ADT). 325 pts (88.1%) and 286 pts (77.5%) were recommended vitamin D and calcium supplementation, respectively. Bone agent use and toxicity are presented in table 1. 110 of 247 pts (44.5%) treated with a bone agent were started in the mHSPC setting without OP/P. Time from mPCA diagnosis to first SRE was a median of 32.8 months (IQR 13.5 to 66.8) for pts who received a bone agent vs. 28.2 months (IQR 8.7 to 59.1) who did not (Chi-squared = 7.089, p = 0.008). Among SREs, 102 pts (27.6%) had a pathologic fracture, 1 (0.3%) severe hypercalcemia > 14 mg/dL, 23 (6.2%) bone surgery, 142 (38.5%) bone irradiation, and 4 (1.1%) spinal cord compression. Conclusions: Bone agent use was associated with an expected improvement in time to first SRE. Pts with mPCA had high rates of vitamin D and calcium supplementation for OP/P prevention. Denosumab was the most used bone agent in concordance with guidelines for mPCA. DEXA scan rates were low, and nearly half of patients received a bone agent prior to castrate resistance. [Table: see text]