Robotic Surgery Expert Dr. David Samadi, MD Discusses FDA Warnings on the Effect of GnRH Agonists

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Oct 27, 2010, 06:27 ET

NEW YORK, Oct. 27 /PRNewswire/ -- Drugs, known as gonadotropin-releasing hormone (GnRH) agonists, may raise diabetes and heart risk and, as a result, now need new warnings. U.S. health officials said the drug used to stem the production of testosterone, the hormone that contributes to prostate cancer growth, could also lead to sudden death. "The risk of diabetes, heart disease and sudden death in men undergoing prostate cancer treatment with these drugs does not appear to be elevated, however patients should be regularly monitored by their doctors for signs of blood sugar increase or heart damage," said Dr. David Samadi, a robotic prostatectomy expert as well as the new Vice Chairman, Department of Urology, and Chief of Robotics and Minimally Invasive Surgery at The Mount Sinai Medical Center in New York City.

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"Doctors need to monitor a prostate cancer patient's risk for diabetes and heart disease before starting any treatment and compare the side effects versus benefits," said Dr. Samadi, a urologic oncologist skilled in robotic prostate surgery. GnRH agonists are approved by the Food and Drug Administration to alleviate symptoms of advanced prostate cancer with androgen deprivation therapy treatment. These include Abbott's Lupron, AstraZeneca's Zoladex, Sanofi's Eligard, Watson Pharmaceuticals' Trelstar, Endo Pharmaceuticals' Vantas, Alza's Viadur, Pfizer's Synarel and several generic versions.

The medical journal Circulation reported in February that various doctors' groups felt androgen deprivation hormone treatment for prostate cancer was believed to increase the risk of heart attack in patients with a prostate cancer diagnosis. Subsequent studies reported by the FDA determined a small increased risk of diabetes or heart disease in patients treated with these drugs. "Prostate cancer patients do not have to stop taking the drugs, but they go to their doctors with any concerns," said Dr. Samadi, "Patients should tell their doctors if they have ever had diabetes, heart disease, heart attack, stroke, history of high blood pressure, high cholesterol or if they are smokers."

All of these medicines for prostate cancer are allowed to remain on the market but must carry new label warnings. The drug manufacturers are currently reviewing the FDA request. "What's important to note is that hormone treatment for prostate cancer is not a fail-safe cure, because even though the therapy can extend survival, the prostate cancer tumors can eventually become immune to therapy," explained Dr. Samadi. Evidence has shown that lowering testosterone is an effective prostate cancer treatment, however lower testosterone levels can induce metabolic syndrome, which contributes to the development of heart disease. Men diagnosed with advanced prostate cancer who are on hormone therapy are at a twofold risk of developing metabolic syndrome.

"I routinely counsel my prostate cancer patients on the risks of weight gain and increased carbohydrate intake and advise them to eat sensibly and exercise in order to reduce their risk of developing metabolic syndrome," said Dr. Samadi, "These GnRH agonists might increase heart disease risks because they cause men to pack on extra weight, and, as usual, appropriate lifestyle choices are the best course of action in preventing prostate cancer or other disease."

GnRH agonists are routinely used in conjunction with radiation therapy, which is why Dr. Samadi advocates the use of robotic prostatectomy over radiation. "It's the only treatment that completely removes the cancerous prostate gland without the need for hormones or radiation, and allows me to determine its stage, level and grade accurately," explained Samadi, "What's the point in preventing these patients from dying of prostate cancer if they are just going to die from heart disease? It makes no sense."