Dr. Roger Rittmaster and Dr. Catherine Lazier, Dalhousie University
An evaluation of 5a-reductase inhibition in a model for intermittent androgen withdrawal therapy (the patient is on hormones to stop the production of testosterone which the prostate cancer feeds on, and once the PSA has reached almost 0, the patient is taken off the hormones for a few months, then cyclically restarts the hormones) in prostate cancer. Androgen withdrawal therapy is very often effective, resulting in prostate tumour regression and a decrease in serum prostate-specific androgen (PSA), but after a period of time, the tumour usually re-grows. Recently there have been very promising results suggesting that continuous androgen withdrawal therapy can be modified to a form of intermittent withdrawal of the hormone. The time period where the patient is not on the hormone treatment, the treatment side effects disappear and overall, very importantly, lead to a longer period of time before the tumour re-grows and becomes hormone treatment unresponsive. This study will test a modified androgen replacement phase in an intermittent therapy animal model, which involves using 5a-reductase inhibitor drugs, which block the conversion of testosterone to dihydrotestosterone. These drugs have very few side effects and their use may further prolong the time before the tumour no longer responds to hormonal treatment.
Dr. Neil Fleshner, Toronto-Sunnybrook Regional Cancer Centre
A study into how our environment may play a critical role in the development of prostate cancer. Oxidative stress is a process by which environmental factors such as dietary fat, smoking and lack of exercise can cause genetic damage to human cells. Genetic damage is a distinguishing feature of cancer cells. This study will assess the role of oxidative damage to prostate tissue in the development and progression of prostate cancer. It will thus provide an insight into the role of lifestyle related factors in the development of prostate cancer. It may also provide a indicator by which researchers can assess the efficacy of nutrition intervention studies.
Dr. Richard Choo, Sunnybrook and Women's College Health Sciences Centre
A prospective phase 2 clinical study to evaluate a novel approach in which the choice between "watchful waiting" or definitive treatment of prostate cancer is determined by the rate of PSA increase or the development of early, rapid clinical and/or histologic progression.
This new strategy offers the ability to individualize therapy according to the biological behaviour of the cancer. This would mean that patients with slowly growing malignancy would be spared the side effects of radical treatment, while those with more rapidly progressive cancer would still benefit from curative therapy.
In the study of 250 patients, it was found that the grade of the disease remained stable in 92% of patients and that less than 5% of patients had radical surgery at two years into the study. Overall, by the end of the five year study, about 16% of the patients had come off the study due to the combination of grade change, PSA increase or tumour progression.
The researchers concluded that, "Watchful waiting is clearly appropriate for patients who are elderly, have significant health concerns, and those who have slow-growing prostate cancer. Many patients, however, fall into a gray zone where the benefits of treatment are unclear. In these patients, close monitoring with selective intervention is appealing."
The Newmarket US TOO Cancer Support Group
The development of a series of videos on prostate cancer. These videos are available to prostate cancer support groups across Canada.