“Androgen deprivation therapy increases the risk of both fragility and non-fragility fractures, and patients and doctors need to be aware of this,” Dr. Shabbir M. H. Alibhai commented in an email to Reuters Health.
Dr. Alibhai with the University Health Network in Toronto, Ontario, and colleagues examined fracture types and associated risk factors among men with prostate cancer, using linked administrative databases. The investigators identified just over 19,000 men with at least 6 months of androgen deprivation therapy (ADT) or bilateral orchiectomy, and matched them by age, cancer treatment, comorbidity, prior fractures and socioeconomic status to the same number of men who had never been on ADT.
As reported in the September issue of the Journal of Urology, during a mean follow-up of 6.47 years there were 3387 fractures of any type among the ADT users and 2495 among the non-users, yielding an adjusted hazard ratio of 1.46 for fracture associated with ADT.
The numbers of fragility fractures of the spine, lower arm, hip or femur in the two groups were 1778 and 1157, respectively, for a hazard ratio of 1.65.
“Independent predictors of fragility and any fracture were increasing age, prior bone thinning medications, chronic kidney disease, prior dementia, prior fragility fracture and prior osteoporosis diagnosis or treatment (p<0.05),” the investigators found.
“We have identified several important, easily clinically identifiable risk factors that increase fracture risk,” Dr. Alibhai said. “This information should supplement a bone mineral density test, which should be done at baseline in all men starting any form of ADT (intermittent or continuous).”
In a related Editorial Comment, Dr. Philip J. Saylor of Massachusetts General Hospital Cancer Center Boston, concurs. “We must move beyond bone mineral density as a stand alone tool to estimate fracture risk.”
Dr. Alibhai advised that calcium and vitamin D should be recommended in all men starting ADT, unless they have contraindications, to reduce the risk of fracture. “Prescription therapies (a bisphosphonate, denosumab, or toremifene) should be tailored to the patient’s risk for fracture, which is based on clinical risk factors (including age), and bone density results.”
Fracture Types and Risk Factors in Men With Prostate Cancer on Androgen Deprivation Therapy: A Matched Cohort Study of 19,079 Men
J Urol 2010;184:918-924.