Asked by Edward Siguel, Rockville, Maryland
What are the best diets and supplements to prevent and treat prostate cancer? What about tomatoes? Or vitamin E? Or antioxidants?
I've heard arsenic may be effective, but some side effects are frequently undesirable.
Dr. Otis Brawley
Chief Medical Officer,
American Cancer Society
There is no definite non-drug prostate cancer preventative. Epidemiologic studies suggest that men who have a diet high in fruits, vegetables, and soy products and low in fat (especially animal fat) may have a lower risk. Also men with diets high in tomato products seem to have a lower rate of prostate cancer. This was especially true of tomato products cooked in olive oil such as tomato sauces. There is growing interest in Vitamin D as a possible correlate with prostate cancer prevention.
These are all epidemiologic correlations. I caution that there have been epidemiologic correlations that when the identified behavior was tested in a controlled study, the behavior did not lower risk. For example studies suggested a correlation between Vitamin E and Selenium and reduced risk of prostate cancer. These hypotheses were tested in a study in which 32,000 men were randomized to a daily selenium pill versus placebo and 32,000 men were randomized to a daily vitamin E pill versus placebo for about five to six years. The men getting selenium and vitamin did not have a lower rate of prostate cancer compared to those getting the placebo and there was concern that selenium might be increasing risk of diabetes and vitamin E might actually be correlated with an increased risk of prostate cancer. The lesson here is be careful adopting things that sound good and have not been tested scientifically.
Some have advocated supplements advertised to promote prostate health and suggested they prevent prostate cancer. It almost always says in the small print that these supplements have not been tested. One should be careful.
The drug finasteride, marketed as Proscar by Merck, has been FDA approved as a medical treatment for benign prostatic hyperplasia or BPH. BPH is a common benign growth of the prostate that makes it difficult to urinate. The drug shrinks the prostate and improves urinary flow symptoms. In a large long term randomized study of finasteride and placebo, it was found that finasteride reduced the risk of prostate cancer by more than 25%. Those who were diagnosed with prostate cancer however had a higher proportion of high grade more aggressive prostate cancers. It has sense been shown that finasteride helps screening find small prostate cancers not that it causes high grade prostate cancers.
There are lots of questions about the benefits, risks and accuracy of prostate cancer screening so studies with finasteride continue.
I know of no data on arsenic and caution that it is a very dangerous compound.
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