According to the results of a study published in the Journal of Clinical Oncology, use of a gonadotropin-releasing hormone (GnRH) agonist for the treatment of non-metastatic prostate cancer may increase the risk of diabetes and cardiovascular disease.
The prostate is a gland of the male reproductive system. It produces some of the fluid that transports sperm during ejaculation. After skin cancer, prostate cancer is the most common form of cancer diagnosed in men.
Androgen deprivation therapy, also known as hormonal therapy, is designed to block testosterone from stimulating the growth of hormone-dependent types of prostate cancer.
Among men with metastatic prostate cancer (cancer that has spread beyond the prostate to distant sites in the body), androgen deprivation therapy is often used to relieve symptoms. Androgen deprivation therapy may also improve survival for some men with earlier stage prostate cancer.
Androgen deprivation can be achieved through the use of medications such as gonadotropin-releasing hormone agonists, or by surgically removing the testicles (bilateral orchiectomy).
Men with early-stage prostate cancer generally have a favorable prognosis, and understanding the frequency of serious treatment-related side effects is an important part of treatment planning. Because androgen deprivation may increase fat mass and insulin resistance, it’s possible that it could increase the risk of diabetes and cardiovascular disease.
To explore the risks of diabetes and cardiovascular disease in men with localized or regional prostate cancer (cancer that has not spread to distant sites in the body), researchers conducted a study among more than 70,000 Medicare enrollees with prostate cancer. Information about medication use and health outcomes was collected from medical claims data.
Overall, 36% of the men had received a GnRH agonist and 7% underwent surgical removal of the testicles.
During four-and-a-half years of follow-up, 5.4% of study participants had a heart attack and 4.5% experienced sudden cardiac death. Among the men who were initially free of diabetes, 10.9% developed diabetes. Among the men who were initially free of coronary heart disease, 25.3% developed coronary heart disease.
- Compared to men who did not receive androgen deprivation therapy, men who were treated with a GnRH agonist were 44% more likely to develop diabetes, 16% more likely to develop coronary heart disease, 11% more likely to have a heart attack, and 16% more likely to experience sudden cardiac death.
- Compared to men who did not receive androgen deprivation therapy, men who underwent surgical removal of their testicles were more 34% more likely to develop diabetes. Risks of coronary heart disease, heart attack, or sudden cardiac death were not increased.
- The researchers note that it’s unclear why the risks of bilateral orchiectomy would differ from the risks of GnRH agonists. It’s possible that the relatively small number of men who underwent orchiectomy may have produced some uncertainty in these results, but the researchers note that additional studies are needed to clarify this question.
The researchers conclude that use of GnRH agonists in the treatment of localized or regional prostate cancer may increase the risk of diabetes and cardiovascular disease. The researchers note that “Decisions about GnRH agonist treatment for locoregional prostate cancer should weigh improvements in cancer-specific outcomes against potential increased risks of diabetes and cardiovascular disease.”
Reference: Keating NL, O’Malley J, Smith MR. Diabetes and Cardiovascular Disease during Androgen Deprivation Therapy for Prostate Cancer. Journal of Clinical Oncology. 2006;24:4448-4456.