More Prostate Cancers Might Be Prevented

Yearly digital rectal exams and PSA screenings revealed that almost 25 percent of the men on placebo went on to develop prostate cancer. However, just a little over 18 percent of those taking finasteride got the disease.

Fleshner and his associates noted, however, that most of the cancer cases prevented appeared to be of the early stage, low-grade variety. More serious, higher-grade disease actually appeared to become more common among patients taking finasteride. This raises concern that the medication might actually hasten disease progression, the Canadian group cautioned.

Nevertheless, their review concluded that finasteride might, in the near future, become an effective prevention tool for men with a strong family history of the disease.

Additional studies are currently under way to explore the benefits of newer hormone manipulation drugs, they noted, including the 5ARI drug dutasteride and the selective estrogen receptor modifier toremifene. Results should be available in a few years.

Meanwhile, the Canadian team also uncovered evidence suggesting that limiting fat in the diet might also reduce prostate cancer risk. Various studies have highlighted unhealthful connections between fat and pesticide exposure, testosterone level increases, and the rise of oxidative stress -- all of which seem to contribute to prostate disease risk.

By contrast, evidence has mounted that increasing vitamin E and selenium intake could also protect against prostate cancer, they said. Recent research also suggests that consuming more green tea, soy, vitamin D, and lycopene (typically found in tomatoes) might confer similar benefits.

Fleshner and his colleagues hailed the new emphasis on prevention. The arrival of even more helpful prevention information might be just around the corner, they said.

"What's exciting now is that there's no doubt any longer that prostate disease is preventable," said Fleshner. "This will not necessarily translate into improved mortality rates, because it may be that we will be able to prevent more low-grade disease than high-grade."

But many men with low-grade disease currently undergo surgery and other treatments that can impact their quality of life, he noted. "So, even if we are able to reduce just the need for unnecessary treatment, this will be a good step," Fleshner said.

Not everyone shares that optimism, however.

Dr. Nelson Neal Stone, a clinical professor of urology and radiation oncology at the Mount Sinai School of Medicine in New York City, believes that when it comes to preventing prostate cancer, "we're still sort of at a loss."

"Today, you can't really advise a patient to do anything to prevent prostate cancer," he said. "The best study so far -- the PCPT study-- did show a 25 percent drop in prostate cancer, but that was in low-grade tumors, whereas the incidence of high-grade tumors may actually have gone up. And a lot of the dietary factors that showed promise --vitamins, selenium -- have come into question as to whether they're really helping patients."

"So, I would agree that in five year's time, we will probably come up with strategies to reduce the clinical incidence of the disease in terms of detecting low-grade cancer," he added. "But that doesn't have much meaning in a patient's life. What has meaning is the ability to prevent a high-grade tumor from metastasizing and potentially ending a patient's life. And nobody has shown that anything can reduce that."

"In my opinion, the best strategy we have now is early detection," Stone said. "If you find a patient with an aggressive prostate cancer, and it's small and in the prostate and you find it early, you save that patient's life."

More information

For more on prostate cancer prevention, visit the U.S. National Cancer Institute.

SOURCES: Neil Fleshner, M.D., head, division of urology, Princess Margaret Hospital, University Health Network, University of Toronto, Ontario, Canada; Nelson Neal Stone, M.D., clinical professor, urology and radiation oncology, Mount Sinai School of Medicine, New York City; Nov. 1, 2007,Cancer