Androgen deprivation therapy roughly doubles fracture risk in prostate cancer patients, BJU International reports. The study also showed that prostate cancer can increase fracture risk up to eight fold.

Previous studies suggested that gonadotropin-releasing hormone (GnRH) agonists and antiandrogens increase bone loss and fracture risk. However, disentangling the fracture risk attributable to ADT from that due to prostate cancer (for example from spinal metastases) proved difficult. The new analysis included 15,716 Danish men aged over 50 years (average age approximately 67 years) who presented with a fracture and 47,149 age-matched controls. Of these, 1.3% of controls and 2.5% of those with a fracture had prostate cancer.

Prostate cancer patients were almost twice and four times more likely to have any fracture or a hip fracture respectively (odds ratios [OR] 1.8 and 3.7 respectively) compared with controls. The risk of hip fractures was particularly pronounced in men aged between 50 and 65 years (OR 8.4). Overall, prostate cancer accounted for 3.1% of hip fractures in Danish men aged over 50 years. The increased fracture risk was evident soon after diagnosis and persisted in long-term survivors: the risk of all fractures and hip fractures was roughly doubled whether patients were diagnosed with prostate cancer two years or less before enrolment or more than six years. No increased risk of vertebral fractures emerged.

Nineteen per cent of the men with prostate cancer had undergone orchidectomy, 9% received ADT and 4% had both. ADT (e.g. GnRH agonists and antiandrogens) and orchidectomy (surgical castration) both roughly doubled the risk of fracture (OR 1.7 for each) in addition to the fracture risk associated with prostate cancer. ADT also doubled (OR 1.9) the risk of hip fracture over the inherent risk associated with prostate cancer.

However, the research only covered the 15% of ADT doses issued on prescription. The method would not capture ADT dispensed by hospitals and is, therefore, likely to underestimate the risk. “These findings indicate a very markedly increased fracture risk in prostate cancer and an additional risk associated with ADT, a risk which is likely to be underestimated in the present analysis,” the authors conclude.

Espicom estimates that the prostate cancer market was worth US$3 billion in 2006 and is growing at more than 5% year on year. Hormonal therapies currently dominate the market. According to Cancer Research UK, doctors diagnose almost 35,000 cases in the UK, accounting for about 12% of all cancers. Around 10,000 men die from prostate cancer each year in the UK.