Avodart & Proscar for Men on Active Surveillance

BY MARK SCHOLZ

More and more men are embarking on active surveillance—close monitoring of their prostate cancer—rather than implementing immediate radical therapy. Of course, only individuals with carefully selected low-grade prostate cancer are eligible for this approach. During the extended observation period many men enquire if there are nontoxic interventions to improve their odds that the cancer will stay dormant. The important issue of diet often arises though that is not the subject of today’s topic. Hormonal treatment, on the other hand, is a treatment that calls for further discussion.

Targeted Hormone Blockade

Blocking testosterone production with testosterone inactivating pharmaceuticals (TIP) is an amazingly effective anticancer maneuver unique to prostate cancer. However, TIP is generally reserved for treating the more aggressive types of prostate cancer since it has potentially unpleasant side effects like impotence, weight gain and reduced muscle strength.  However, there is a way that hormonal therapy can be targeted to specifically block testosterone activity inside the prostate while sparing the rest of the body from negative side effects. Proscar and Avodart—both FDA-approved medications to shrink the prostate gland function by this very mechanism. They block a special form of testosterone called dihydrotestosterone (DHT) that only occurs inside the gland.  The general public is familiar with these medications due to their ability to reduce the size of the prostate gland and ameliorate a common problem familiar to aging men:  the need to get up frequently at night to urinate.  Yet thanks to their lowering effect on DHT, these drugs also have anti-cancer effects.   

The Benefits of Proscar and Avodart for Fighting Prostate Cancer

The effect of Proscar and Avodart against cancer have been evaluated in several double blind placebo controlled trials.  In one trial 18,000 men¹ were treated with Proscar or placebo for seven years. Ten thousand of these men then underwent a prostate biopsy. The Proscar treated men were 25% less likely to be diagnosed with prostate cancer, compared to the men treated with placebo. In two other double blind placebo controlled trials, Avodart was also shown to reduce the risk of a prostate cancer diagnosis by about 22%.^2,3

More recently, in a study reported in abstract form at the American Society of Clinical Oncology in March this year, 302 men on active surveillance were given either Avodart or placebo for 3 years. As is typically the case with men on active surveillance, repeat prostate biopsies were performed 18 and 36 months after the initial diagnosis to determine if the cancer was progressing.  Men who received Avodart had a progression rate that was 38% less than the men on placebo.

Another study published in European Urology retrospectively evaluated 288 men on active surveillance who received Avodart or Proscar that were compared to men who received neither.  After three years of observation, the biopsy progression rate was 50% lower—18% for the men on treatment vs. 36% for the men on no treatment.⁴

Is There a Downside Risk?

Given that Avodart and Proscar lower PSA by about 50%, the question becomes: “Are they masking the capacity of PSA to detect cancer progression?”  The answer is no.  PSA still rises in men with progressive disease.  In fact, studies show that Avodart and Proscar improve the accuracy of the PSA monitoring process, enhancing the likelihood of detecting High-Risk cancer.⁵  The standard approach in our practice is to offer Avodart or Proscar to all our patients on active surveillance. 

When taking these pills, about one out of five men will notice a modest reduction in their sex drive.  This reduction in libido may fade away after a few months with continued treatment.  Even so, if a reduction in libido occurs, we often simply advise stopping the medication since these medications are not essential to the active surveillance approach but rather an optional enhancement.

References

1. Ian Thompson, The influence of finasteride on the development of prostate cancer. The New England Journal of Medicine, July 2003.
2. Gerald Andriole, Effect of dutasteride on the detection of prostate cancer in men with benign prostatic hyperplasia. UROLOGY, 2004.
3. Gerald Andriole, Further analysis from the REDUCE prostate cancer risk reduction trial. The Journal of Urology, April 2009.
4. Antonio Finelli, Impact of 5-Alpha-Reductace inhibitors on men followed by active surveillance for prostate cancer.  European Urology, Vol. 59; 509.
5. Ian Thompson, Effect of finasteride on the sensitivity of PSA for detecting prostate cancer. Journal of the National Cancer Institute, August 2006.