Incidence of skeletal-related events (SREs) among prostate cancer patients.

Abstract

e16035 Background: Skeletal related events (SREs) occur in men with prostate cancer and may result from both bone metastases and exposure to androgen deprivation therapy (ADT). The objective of this study was to quantify the incidence of SREs in patients with prostate cancer treated with ADT or orchiectomy in clinical practice. Methods: Prostate cancer patients served by Henry Ford Health System (HFHS) were identified via the HFHS tumor registry. Eligible patients were newly diagnosed with prostate cancer between 2004 and 2010 and treated with ADT or orchiectomy. Comprehensive population-based data were compiled using tumor registry with linkages to pharmacy, laboratory results, and healthcare encounter databases. SREs included spinal cord compression, surgery to bone, pathologic fracture and radiation to bone. Disease progression and metastases were identified by medical record review. Results: We identified 702 patients with prostate cancer and receipt of ADT or orchiectomy; 57.6% were >70 years of age and 43.7% were African American. 56.3% of patients were initially diagnosed at AJCC stage II, 9.8% at stage III, 22.1% at stage IV, and 11.8% had missing or unknown stage. A total of 93 patients (13.2%) had one or more SREs: radiation to bone (8.5%) and spinal cord compression (3.1%) were the most common SREs. We then limited the cohort to patients initially diagnosed with or progressing to AJCC stage IV prostate cancer (N=207). Among this group, 47.8% were >70 years of age. The mean time from stage IV diagnosis to end of follow-up was 35.6 months. In this subgroup, 16.4% of patients were initially diagnosed at AJCC stage II, 8.2% at stage III, 69.6% at stage IV, and 5.8% had missing or unknown stage. 57 patients (27.5%) had one or more SREs. Conclusions: Some clinical trials have found 36-41% of high-risk metastatic prostate cancer patients developed SREs during 3 years of follow-up. In this population-based cohort of patients with prostate cancer receiving ADT or orchiectomy and treated in real-world clinical practice, we found the incidence of SREs to be lower than what has been reported in clinical trials. Additional analyses exploring the incidence of SREs in patients diagnosed with metastatic castrate resistant prostate cancer will be presented.