Expert discusses androgen deprivation therapy for prostate cancer

Dec 9 2010

A common prostate cancer treatment, the ‘androgen deprivation therapy’ has often been prescribed for low-risk prostate cancer patients. This therapy for treating prostate cancer had previously been blamed for increased risk of cardiovascular disease and heart conditions.

However, this hormone treatment for prostate cancer has now become more controversial due to its two potential side effects, diabetes and obesity, which are risk factors for colorectal cancer. "Androgen deprivation therapy is overused, and now may be even more dangerous than previously thought," said Dr. Samadi, a robotic prostatectomy expert, as well as the Vice Chairman, Department of Urology, and Chief of Robotics and Minimally Invasive Surgery at The Mount Sinai Medical Center in New York City.

The University of Michigan study, which appears in the December issue of the Journal of the National Cancer Institute, found that androgen deprivation therapy, delivered via injections or surgical castration, resulted in a 30 to 40 percent increased risk for colorectal cancer. However, the absolute risk is small, no more than a 2.5 percent absolute risk of colorectal cancer over a five-year period.

"When treating late-stage prostate cancer that has spread beyond the prostate gland, it is effective," said Dr. Samadi, "When coupled with radiation, it can be very beneficial in treating locally advanced prostate cancer." However, the study showed that as a primary therapy for lower-risk or localized prostate cancer tumours there is no substantial evidence support for the androgen deprivation therapy.

Furthermore, analysts are still assessing the prostate cancer screening test, prostate-specific antigen (PSA), stating that it results in unnecessary prostate cancer treatment, something Dr. Samadi does not believe. "The androgen deprivation therapy risk just further complicates the whole prostate cancer treatment issue," he said, "Androgen deprivation therapy patients are undergoing the procedure when there is an elevated PSA as a result of a biochemical tumour recurrence. So the benefit is not definitive," says Samadi.

Additionally, the length of time patients received the hormone therapy increased their risk of developing colorectal cancer. Men who had their testicles removed had the highest risk. "Obesity has always been a significant risk factor, especially for men, for a wide variety of diseases, including colorectal cancer," said Dr. Samadi, a da Vinci prostatectomy expert who is also skilled in open prostatectomy as well as laparoscopic prostatectomy, "Obese men have lowered androgen levels, which suggests a direct link to colorectal cancer development."

Critics of the study believe that men receiving a prostate cancer diagnosis usually undergo colorectal cancer screening for the first time, so cancer is detected only because of screening and not the hormone treatment for prostate cancer. A study would have to be conducted to assess the incidence of colorectal screening in men who received hormone therapy, a radical prostatectomy or no treatment.

Dr. Samadi explained that random biopsies are not accurate enough to make inferences of the entire prostate treatment. Therefore it is insufficient to provide doctors with enough information on staging. "Not many patients realize that there is usually a 40 percent upgrading of the disease after the prostate is removed, which is also a strong argument against radiation as the primary treatment for prostate cancer," he said.

"Hormones and radiation go hand in hand and with all of the inherent risks, which is why I prefer prostate removal surgery and providing a total cure for patients," said Dr. Samadi, "However, this study highlights the continued need for a routine colorectal cancer screening and better lifestyle habits, such as exercise, to help diseases such as colorectal cancer” he opined.