Fracture risk in men with prostate cancer: a population-based study.

Fractures are increased among men with prostate cancer, especially those on androgen-deprivation therapy (ADT), but few data are available on men with localized prostate cancer. The purpose of this investigation was to estimate fracture risk among unselected community men with prostate cancer and systematically assess associations with ADT and other risk factors for fracture. In a population-based retrospective cohort study, 742 Olmsted County, MN, men with prostate cancer first diagnosed in 1990-1999 (mean age 68.2 ± 8.9 years) were followed for 6821 person-years. We estimated cumulative fracture incidence, assessed relative risk by standardized incidence ratios, and evaluated risk factors in time-to-fracture regression models. All together, 482 fractures were observed in 258 men (71 per 1000 person-years). Overall fracture risk was elevated 1.9-fold, with an absolute increase in risk of 9%. Relative to rates among community men generally, fracture risk was increased even among men not on ADT but was elevated a further 1.7-fold among ADT-treated compared with untreated men with prostate cancer. The increased risk following various forms of ADT was accounted for mainly by associations with pathologic fractures (14% of all fractures). Among men not on ADT (62% of the cohort), more traditional osteoporosis risk factors were implicated. In both groups, underlying clinical characteristics prompting different treatments (indication bias) may have been partially responsible for the associations seen with specific therapies. To the extent that advanced-stage disease and pathologic fractures account for the excess risk, the effectiveness of fracture prevention among men with prostate cancer may be limited.