857P - Baseline fracture risk in men with prostate cancer starting the STAMPEDE trial

Androgen deprivation therapy (ADT) for prostate cancer (PC) increases fracture risk. In non-cancer populations, FRAX, a fracture risk assessment tool, is used routinely to calculate 10-year probability of major osteoporotic fracture (MOF; spine/hip/forearm/humeral fractures) and hip fracture alone to determine the need for bone density (BMD) assessment and/or treatment. We calculated FRAX using risk factors at entry to the large STAMPEDE PC study. STAMPEDE includes men with newly diagnosed metastatic/high risk non-metastatic PC about to commence ADT, randomised to add or substitute other therapies. Our pre-planned analysis included 6379 men, 86% of enrolment at the time of analysis (2018) for whom FRAX clinical risk factors (excluding femoral neck BMD) were collected prospectively. Secondary osteoporosis in FRAX was set to ‘yes’ for all, as they were about to receive ADT. Glucocorticoid use was set to ‘yes’ for men allocated to abiraterone due to potentially long concomitant use, but not for those allocated shorter treatment with docetaxel. Baseline characteristics for this largest dataset of its kind, are shown below. The mean (SD) baseline FRAX 10-year probability was 3.06(2.96)% for hip fracture and 8.70(4.02)% for MOF. Risk increased with increased age at entry, eg MOF probability at age 50-54 years was 4.9% rising to 11.3% in those aged 75 years or older. Using UK National Osteoporosis Guideline Thresholds, 2221 (34.8%) men were classified as high/intermediate risk (meriting BMD scan).The need for BMD assessment varied across planned treatment arms (18.4% in men receiving ADT only to 80.0% in men also planned to receive abiraterone).Table857PTableCharacteristicRandomisation years2006- 2018Age (y)67.4±7.2Height (cm)174.7±6.9Weight (kg)85.6±14.8BMI (kg/m2)28.0±4.5Prevalence of FRAX risk factors (%) Previous fracture after age 50yr6.1Glucocorticoid use (≥4mo)27.4Parental hip fracture7.7Rheumatoid arthritis2.4Alcohol (≥3 units daily)15.5Current smoking11.5 FRAX fracture risk assessment in men starting ADT suggests 1 in 3 require BMD assessment to decide on the need for bone protection. Planned treatment in addition to ADT, rather than age, was the main determinant for consideration of bone health. 2004-000193-31. University of Sheffield. University of Sheffield. J.E. Brown: Honoraria (self), Research grant / Funding (institution): Amgen; Honoraria (self), Research grant / Funding (institution): Novartis; Honoraria (self), Research grant / Funding (institu