IN seeking ways to prevent prostate cancer, medical research has frequently turned to the supermarket. Walk around a grocery store and you'll find subjects of intense scientific scrutiny in the produce section (vegetables, especially broccoli), condiment aisle (ketchup and tomato sauce) and vitamin shelf (vitamin E and selenium).
In recent years, however, much of the promising research has involved common products found in the pharmacy. Scientists believe that several familiar medications, already used by millions to treat other conditions, may have a new role: helping to lower the toll of prostate cancer, which kills about 30,000 American men each year.
For The Record
Los Angeles Times Monday October 31, 2005 Home Edition Health Part F Page 8 Features Desk 1 inches; 35 words Type of Material: Correction
Selenium -- An article about nutritional supplements in the Oct. 17 Health section said a study found lower rates of prostate cancer among men who took 200 milligrams of selenium. The dose was 200 micrograms.
So far, only one treatment has been shown in a large, well-designed study to reduce the risk of prostate cancer: finasteride, a drug widely used to relieve urinary problems. Sold as Proscar, finasteride shrinks an enlarged prostate that can block urine from traveling through the urethra. It works by preventing testosterone from converting into a related chemical -- dihydrotestosterone -- that promotes prostate growth. However, because the drug slows cell division in the prostate, it also reduces the occurrence of cancer-causing mutations.
In a blockbuster study published in 2003 in the New England Journal of Medicine, researchers at the University of Texas followed more than 18,000 men over seven years and found that men who took five milligrams of finasteride every day cut their risk for prostate cancer by 25%.
Despite those encouraging results, doctors have been reluctant to prescribe finasteride to prevent prostate cancer, says Dr. Eric Klein, head of urologic oncology at the Cleveland Clinic's Glickman Urological Institute. The reason: The Texas study also found that men who took finasteride had a slightly increased risk of developing an aggressive form of prostate cancer -- the type most likely to be fatal.
Klein points out that the risk is very slight -- only about 1%. And he says that even this small risk may be overstated, because finasteride, by shrinking the prostate, may have made aggressive tumors easier to detect. A research paper to be published in the coming months will report that the actual risk of aggressive prostate cancer from finasteride is probably lower than the Texas study suggests, Klein says. "I think the whole community will reassess the use of finasteride after this data is out and we'll see an interest in prescribing it more widely to prevent prostate cancer."
