Cancer Therapy Elevates Risk of Disease

Recipients of a frequently prescribed hormone therapy for prostate cancer are at higher risk of developing diabetes and cardiovascular disease, a Harvard Medical School study has found.

The study, published last week in The Journal of Clinical Oncology, found that men receiving “GnRH agonist” hormone therapy faced a 44 percent greater risk of diabetes and a 16 percent greater risk of coronary disease when compared to those not receiving the hormones.

“Patients and physicians need to be aware of the elevated risk as they make treatment decisions,” said study co-author Nancy Keating, an assistant professor of health care policy and medicine at Harvard Medical School.

The American Cancer Society estimates that one in six American men are diagnosed with prostate cancer during their lifetimes, making it the most common form of cancer among American men. The society predicts that a total of 234,460 people will be diagnosed with the disease this year.

“GnRH agonist” therapy, the focus of the study, involves injecting a synthetic version of the reproductive hormone GnRH, which blocks the production of testosterone, thereby preventing the spread of prostate cancer.

Authors of the study are questioning the benefits of the treatment because although prostate cancer can be lethal, it spreads slowly, develops primarily in men over 65, and most patients survive for at least five years after they are diagnosed.

The disease’s slow progression raises doubts about whether it is worthwhile to use a potentially hazardous therapy in treating early-stage prostate cancer.

Patients with advanced forms of cancer in need of immediate treatment can take actions to alleviate the increased risks associated with the therapy.

“For men who do require this treatment, physicians may want to talk with their patients about strategies, such as exercise or weight loss, which may help to lower risk of diabetes and heart disease,” said study co-author Matthew Smith, a Harvard Medical School associate professor, in the release.

Researchers also found that another treatment for prostate cancer, surgical removal of testicles, exhibited an increased risk of diabetes but no noticeable increase in the risk of cardiovascular disease or heart attacks.

The researchers have not identified the exact connection between the treatment and increased risk of diabetes and cardiovascular disease, and are planning to further study the therapy.

“We want to try to tease apart some potential risk factors for who’s likely to do better or worse on these drugs...seeing whether the increased risk remains elevated when men are taken off the drugs,” Keating said.