Clinical fracture associated with androgen deprivation therapy: A retrospective study of early phase clinical trial cohorts.

Abstract

234 Background: Androgen deprivation therapy (ADT) is the mainstay treatment in both locally advanced and metastatic prostate cancer. Unfortunately, ADT is associated with rapid loss of bone mineral density (a surrogate for fracture risk) within the first 12 months of initial therapy. Methods: A retrospective review of early phase NCI clinical trials from 2006 to 2013 was conducted to assess the risk of fracture for prostate cancer patients treated with ADT. Results: Seven clinical trials of prostate cancer patients who received ADT between 2006 and 2013 were identified. A total of 464 patients were enrolled in the trials. Patient median age was 64 years, the majority were white (90%), and had good performance status. The median baseline prostate specific antigen level was 29.3 ng/ml and the majority of patients had a Gleason score pattern of >7 (71%). Disease was characterized as involving bone only in 43% of patients and multiple sites (bone, node and/or visceral) in 35%. Of 381 patients for which data were available, 36% received prior hormonal therapy, 37% underwent surgical castration, and 16% received radiation therapy. The most common grade 1-2 adverse events reported in the 7 trials were fatigue (36%), followed by hot flashes (27%), anemia (17%) and hyperglycemia (15%). The most common grade >3 adverse events reported were hypertension and hyperglycemia (3% each). Of the total 464 patients, 7 (0.4%) reported having a fracture (5 were baseline and 2 developed while on treatment). Conclusions: Our study reconfirms the association between clinical fracture and ADT exposure; however, the incidence of fracture rate was less than 1%, which was lower than the published population-based cohorts. The difference could be attributed to short-term ADT exposure, and short-duration of follow up. Clinicians should educate patients about risk of fracture with ADT and offer bone health agent earlier in patients at high risk for fracture and also with underlying co-morbidities such as diabetes, poor performance status, chronic steroid use, or undergo radiation therapy.