Family history (FH) of prostate cancer (PC) is a known risk factor for development of the disease. Although it is thought to influence prognoses, patient follow-up, and treatment decisions, it is not apparent whether a FH of PC is associated with worse clinical outcomes, requiring intensive therapeutic modalities such as chemotherapy. This post hoc analysis of the TRUMPET study was performed to compare baseline characteristics, treatment patterns, and clinical outcomes between patients with metastatic castration-resistant PC (mCRPC) who had a FH of PC and those who did not. TRUMPET is a prospective, observational, multicenter study that enrolled 1028 adult male patients from March 2015 to September 2019 who initiated treatment for CRPC from 147 urology and oncology sites in the US. Patients with and without a self-reported FH of PC (paternal, fraternal, or "other") were included in this post hoc analysis. Genetic test results were not collected for the registry. Patients with missing FH information and those with nonmetastatic CRPC at baseline were excluded. Patients were enrolled within 90 days from the time of decision to treat or treatment initiation. Baseline characteristics and treatment patterns were analyzed descriptively; clinical outcomes (radiographic progression, prostate-specific antigen [PSA] progression, overall survival, and opiate initiation [OI]) were analyzed using the Kaplan–Meier method and Cox proportional-hazards models. Patients with mCRPC and FH (n=200) or no FH (n=631) were included: median age, 72.0 vs 73.0 years; Eastern Cooperative Oncology Group score 1, 29.0% vs 34.1%; median duration from initial PC diagnosis to baseline visit, 5.46 vs 4.61 years; median PSA level at PC diagnosis, 14.27 vs 16.10 ng/mL; clinical M1-stage at diagnosis, 21.5% vs 24.8%, respectively. Primary treatment before CRPC diagnosis in FH and no-FH groups was active surveillance in 21.5% vs 16.6%; radical prostatectomy, 40.0% vs 30.6%; and radiation therapy, 49.0% vs 45.2%, respectively. Initial mCRPC treatment included: chemotherapy, 8.5% vs 6.5%; novel hormonal therapy (NHT), 55.0% vs 59.7%; and immunotherapy, 44.0% vs 37.2%, respectively. After therapy initiation, no differences were seen in radiographic or PSA progression (Table). FH group had a significantly lower risk of death (HR: 0.66, P=0.003), 1-year longer median survival (Figure), and a trend toward a lower risk of OI (Table). After advancement to mCRPC and receiving at least first-line therapy, patients with a FH of PC have a similar radiographic and PSA progression but a significantly lower risk of death than those without FH. More than half of these patients received NHT and <10% received chemotherapy as initial therapy, indicating that hormonal treatments might be useful in these patients. These findings suggest further research is warranted to better understand the role of prostate cancer family history on clinical outcomes and treatment patterns. [ABSTRACT FROM AUTHOR]