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June 2008 Volume 2 #2
 Dr. Goldenberg to speak in Calgary Intermittent hormone therapy PCa prevention with finasteride CPCN executives welcomed in Ottawa • SUBSCRIBE • contact the editor • visit the cpcn website |
Intermittent hormone therapy: What's new?  When Norm Oman was diagnosed with prostate cancer, he asked his doctor about intermittent hormone therapy --- a treatment protocol known to the medical profession as intermittent androgen suppression (IAS) or intermittent androgen deprivation (IAD). "It was very experimental at the time," says Norm. "I knew I wanted enough treatment, but hormone therapy can be really rough on the body --- low energy levels, weight gain, sometimes ED." So the opportunity to have the benefits of hormone therapy while enjoying breaks from this treatment was very attractive to Norm. "We decided to go for it and monitor the situation carefully." Norm's situation then was similar to that of many men whose doctors have recommended intermittent androgen suppression therapy today.What is this protocol, which is currently undergoing phase III trials? To understand, we need to know a little general information about hormone therapy. First, the medical profession has known for a long time that male hormones, such as testosterone, drive the growth of prostate cancer. Take away these hormones, known as androgens, and you take away the environment that prostate cancer needs to grow and flourish. (See the CPCN web page on hormone therapy.) Increasingly, drugs that interfere with the production of androgens or that block the effects of androgens are prescribed to men whose prostate cancer has spread outside the prostate gland, whose cancer appears to have returned after they have undergone surgery or radiation treatment, or who are at a high for recurrence. And, most often, their cancers are controlled well by this hormone therapy, at least initially. But there are complications. Hormone therapy can have side effects, such as loss of libido, erectile dysfunction, hot flashes, night sweats, osteoporosis, anaemia, fatigue, and loss of muscle mass. But more important, although hormone therapy works well to control prostate cancer (often for many years), eventually, in almost all men undergoing this therapy, the prostate cancer cells discover a way to grow without the presence of male hormones. They become "androgen independent," and a man's cancer begins to grow, his prostate-specific antigen (PSA) level increases, and he experiences worsening symptoms. Medical researchers and physicians, among them Dr. Larry Goldenberg, developed intermittent androgen suppression (IAS) as a response to these two problems: the side effects sometimes experienced by men on hormone therapy and the fact that, over time, hormone therapy no longer controls prostate cancer growth. The thinking was that stopping hormone therapy periodically and then restarting it would enable men to enjoy a better quality of life during off-treatment times and might postpone the day when the drugs no longer worked to control their cancer. In the 1990s, studies conducted in the lab using mice were promising. One reported that IAS prolonged threefold the time that it took cells to reach androgen independence, from 50 to 150 days. (See abstract of "Effects of intermittent androgen suppression on androgen-dependent tumours.") These studies sparked a number of clinical trials exploring how effective IAS was outside the lab --- as a treatment protocol for men with prostate cancer. Goldenberg and fellow researchers at the University of British Columbia helped to define the optimal time to stop and restart hormone therapy by observing the responses of 47 men to IAS. The study concluded that intermittent androgen suppression works to control prostate cancer, affords "improved quality of life when the patient is off therapy," and "results in reduced toxicity and cost of treatment." (See an abstract of "Intermittent androgen suppression in the treatment of prostate cancer.") This and numerous other studies taught some valuable lessons. Restarting hormone therapy after it was stopped worked. In other words, if a man's cancer responded to hormone therapy initially, it still responded after a "time out." Most men experienced a 6- to 9-month off-treatment phase after their first treatment, which usually lasted from 9 to 12 months. A few men, especially those with localized disease, had treatment holidays lasting 3 years or longer. Norm reports that his first treatment break lasted from between 18 months to two years. "We didn't know much about when to begin treatment again in those days," he states. "It became a matter of at what time do you loose your nerve." "But I did feel fine, very healthy," Norm reports. The research concurs. Although some phase II trials suggested that regular, continuous hormone therapy improved men's quality of life in terms of controlling pain and urinary symptoms, most men reported an improved overall sense of well-being during the off-treatment phase of IAS. Significantly, men on IAS reported less psychological distress, fewer hot flashes, and more energy, as well as improvements in libido and sexual function, during the off-treatment phase. The most important question is awaiting the results of further phase III clinical trials. How do survival times of men on IAS compare with those of men on traditional hormone therapy? One such trial, headed up in Canada by Dr. Laurence Klotz, is comparing continuous androgen suppression with intermittent androgen suppression as a treatment for patients whose rising PSA levels indicate that their cancer has come back after radiation therapy but who show no clinical signs of metastatic disease. (The official title is equally a mouthful: A Phase III Randomized Trial Comparing Intermittent Versus Continuous Androgen Suppression for Patients With Prostate-Specific-Antigen Progression in the Clinical Absence of Distant Metastases Following Radiotherapy for Prostate Cancer. Click here for more information.) Still, most conclude that intermittent androgen suppression can ameliorate the short- and long-term side effects associated with continuous androgen suppression and is a reasonable alternative, as long as men are fully informed that the therapy is still being investigated and that mature research results are not yet available from some significant clinical trials. And what about Norm? How is he doing? "Healthy and going strong" is the verdict, and still interested in innovations in prostate cancer research. |
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