"Doc, my father had prostate cancer. Is there anything I can do to prevent myself from getting it?"
It's a question that I'm often asked. A recent study in the New England Journal of Medicine has reaffirmed that the answer is "Yes," but it's not that simple. Dutasteride, known by the brand name Avodart, was proven to reduce the risk of developing prostate cancer by 23 percent. So should every man start taking it? I'll answer that by going over some of the details of the study.
Study details. The study examined over 6000 men without prostate cancer who were randomly assigned to taking Avodart or a placebo for 4 years. Prostate biopsies were performed at 2 and 4 years after starting treatment to determine if they had developed prostate cancer. Overall, the men taking Avodart were 23 percent less likely to be diagnosed with prostate cancer than those taking the placebo. However, they had the same rate of intermediate and high risk cancer (combined), and the Avodart patients were actually more likely to be diagnosed with high risk cancer after 4 years. It should be noted that the number of patients diagnosed with high risk cancers was very small (13 patients).
How does it work? It appears that Avodart works by either shrinking tumors or preventing them from growing. The reasoning behind this is complex, but is related to the fact that we can never truly know that a man does not have prostate cancer while his prostate is still in his body. The prostate biopsies we perform only take a very small sample of the prostate to analyze under a microscope. We try to take a representative sampling and can find most cancers, but small tumors can easily be missed by the needles. Thus it appears that Avodart might not be preventing the development of prostate cancer, but rather the ability of us to detect it.
Does Avodart cause high risk cancers? It is unlikely, but we can't be certain just yet. It appears that the tumors that it shrinks are the less aggressive, lower risk ones that aren't as dangerous. By making the tumors too small to detect, it's possible that the small tumors had more time to become more aggressive. Another, similar possibility is that such higher risk tumors would have developed in the placebo patients that were removed from the study because they had prostate cancer diagnosed after two years.
Other than prostate cancer prevention, are there any other benefits to Avodart? What about side effects? Avodart was originally designed to treat an enlarged prostate (BPH). Thus men taking Avodart were less likely to develop an inability to urinate or a urinary tract infection, and fewer needed surgery for their BPH. It also may help with male-pattern baldness (Avodart's sibling, Finasteride, is also known as Propecia). The side effects were quite tolerable, as only 5 percent of men had to stop taking the medication, most commonly for diminished sex drive. One thing that should be noted is that it reduces your PSA level, which we use to monitor people for prostate cancer, by half. You should remind your doctor that you're on Avodart when you get your yearly PSA test.
Should you start taking Avodart? It depends. For those at high risk of developing prostate cancer (a father or brother with prostate cancer or African-Americans) it may be worth it. If you are already taking a medication for your BPH, or are having problems urinating due to BPH, Avodart can kill two birds with one stone. However, it remains unknown whether preventing the less aggressive tumors will have any meaningful long-term benefit for patients.
It is unclear whether this report will lead to increased enthusiasm for prostate cancer prevention. A very similar study of finasteride came out in 2004 with nearly identical results, yet very few men are currently taking it for prostate cancer prevention. But if you are interested in potentially reducing your risk of prostate cancer, you should talk to your doctor or urologist about it.