Dutasteride vs Low Grade Prostate Cancer

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AUTHOR:
Alvin B. Lin, MD, FAAFP

 
Dr. Lin is an associate professor of family and community medicine at University of Nevada School of Medicine and an adjunct professor of family medicine and geriatrics at Touro University Nevada College of Medicine. He also serves as an advisory medical director for Infinity Hospice Care and as medical director of Lions HealthFirst Foundation. Dr. Lin maintains a small private practice in Las Vegas, NV. The posts represent the views of Dr. Lin, and in no way are to be construed as representative of the above listed organizations. Dr. Lin blogs about current medical literature and news at http://alvinblin.blogspot.com/.

Low grade cancer is a very difficult concept for most people to consider. To the average layperson, cancer is binary and digital. It's either present or not. However, to the clinician, especially the oncologist, cancer is really analog; in other words, there are various degrees of relative badness. For instance, if I had to have a cancer but was also given the opportunity to choose which kind of cancer, I'd pick a simple basal cell carcinoma since they're easy to eradicate and very rarely metastasize (spread) rather than melanoma, which has the opposite characteristics.

For most men, when we hear about prostate cancer, all we can think of is dying a slow and painful death from bone metastases and bladder obstruction, or something like that. However, as we're now beginning to discover, there are various grades of prostate cancer as denoted by Gleason score. And in fact, localized (not yet having spread) prostate cancer with a low Gleason score can often be actively monitored (otherwise known as watchful waiting) without any loss of continence, erectile function, or quality-adjusted life years.

Which brings me to a randomized, double-blind, placebo-controlled study published last week in Lancet, which concluded that dutasteride taken daily for 3 years compared to placebo could decrease the risk of low grade prostate cancer from progressing onward to high grade disease. Specifically, the authors noted that only 38% of those randomized to the 5 alpha reductase inhibitor progressed while 48% randomized to placebo had biopsy proven progression. As expected, those randomized to dutasteride (24%) complained more of side effects such as decrease in libido, breast enlargement, and/or nipple sensitivity than those randomized to placebo (15%).

While the above study might make the use of dutasteride as chemoprophlaxis against prostate cancer, let's not forget another study published almost 2 years ago in NEJM in which it appears that dutasteride might increase the risk for high grade cancer, even while lowering one's risk for low grade disease. Of course, the editorial for this latest study brought up the question of why even screen if there is no benefit to be gained. After all, the recent analysis of the ongoing PLCO trial demonstrated no mortality benefit after 13 years of annual screening for prostate cancer.

Clearly, there is no easy answer. Each man will need to assess his risk aversion versus tolerance in order to make an informed decision with the assistance of his family physician.