Prostate news article, April 2005
| GONADOTROPHIN
RELEASING HORMONE ANALOGUES CAUSE OSTEOPOROSIS AND AN INCREASED
RISK OF FRACTURE
Shahinian et al. Risk of fracture after androgen deprivation for prostate
cancer. Reviewed by: Dr Charlotte Foley MA BMBCh MRCS |
A mainstay of treatment for prostate cancer is to lower testosterone using gonadotrophin releasing hormone (GnRH) analogues (Zoladex or Prostap) or surgical removal of both testicles (bilateral orchidectomy). As more and more men receive this treatment for longer periods of time, we are learning more about its long term consequences. Common side effects are reduced libido, impotence, lethargy, muscle wasting, depression and osteoporosis. In particular, the risk of fracture has been established by doctors writing in the New England Journal of Medicine (Shahinian et al, January 13th 2005).
Androgen withdrawal therapy accelerates bone loss, reducing bone mineral density which is strongly associated with an increased risk of fracture. Using a registry of 50,613 American men, the number of fractures suffered within five years after a new diagnosis of prostate cancer was compared between men who received androgen deprivation therapy and those who did not.
Overall, those on hormone withdrawal experienced more fractures. In terms of "number needed to harm", one fracture resulted from every 16 men treated with orchidectomy and every 28 with GnRH analogues. The risk of fracture also increased the more doses of GnRH analogues that men had received. Orchidectomy always conferred the same or greater risk of fracture than drug injections.
The authors concluded that more careful consideration was required of the indications for this treatment given the risks accompanying the benefits. Furthermore, treated men should have their bone mineral density monitored, and be given intravenous bisphosphonate infusions if required.