One of the principal treatments for prostate cancer involves blocking testosterone production. This can be done by castration (removal of the testes), but not surprisingly, most men opt for a hormone based treatment that blocks the production of testosterone by chemical means. Known as gonadotropin-releasing hormone (GnRH) agonist, the drugs are the main therapy for metastatic prostate cancer. Many oncologists believe it also may also improve survival for some men with locally-advanced cancers. But a new study, reported in the Journal of Clinical Oncology, has found that regular injections of GnRH agonist may also put men at an increased risk of diabetes and cardiovascular disease. "Men with prostate cancer have high five-year survival rates, but they also have higher rates of non-cancer mortality than healthy men," said study author Nancy Keating, at Harvard Medical School. "This study shows that [GnRH agonist treatment] may put men at significant risk for other serious diseases."
Earlier studies found GnRH agonists to be associated with obesity and insulin resistance, a precursor to diabetes. But the new study put numbers to the association and found that men with local or regional prostate cancer receiving a GnRH agonist had a 44 percent higher risk of developing diabetes and a 16 percent higher risk of developing coronary heart disease than men who were not receiving hormone therapy.
"Doctors should think twice about prescribing GnRH agonists in situations for which studies have not demonstrated improved survival until we better understand the risks of treatment," said co-researcher Matthew Smith. Keating added that, given the number of men receiving GnRH agonists, often for many months or years, these increased risks can have important implications for the health of prostate cancer survivors.
The study concluded that men should be aware of the elevated risks associated with GnRH agonist treatment, and may want to consider strategies such as exercise and weight loss to help lower the risk.
Based on material from Harvard Medical School
