Selenium: New entry in fight against prostate cancer

PROSTATE CANCER: description risk symptoms treatment prevention Choose a link above to learn more about prostate cancer. Source: WebMD

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June 17, 1999
Web posted at: 1:44 p.m. EDT (1744 GMT)

In this story: Selenium decreases prostate cancer rate Holistic urology clinic looks to selenium and beyond Self-help and supplements still not enough RELATED STORIES, SITES

By Senior Medical Correspondent Dan Rutz

(CNN) -- Evidence is mounting that selenium, a little-known trace element, can help protect against one of the most common cancers in men. Researchers at the University of Arizona have shown in preliminary studies that daily selenium supplements cut the rate of prostate cancer by more than half. Now, new research is under way to see if selenium might also help those who already have prostate cancer.

The Rev. Lester Plattner, diagnosed three years ago, decided against surgery or other radical treatment. "I just didn't want to go through a series of shots and through radiation and anything like that," he said. "And if the Lord wants me, he knows where I'm at, and he can get me anytime he wants me."

It is not unusual for men Plattner's age, 79, to forgo treatment for prostate tumors. Typically, such cancers diagnosed after age 70 are slow-growing. Proponents of what doctors call "watchful waiting" reason that many older men are likely to die of other causes before their cancer ever poses a threat.

But Plattner is very much interested in improving the odds. As part of the "Watchful Waiting with Selenium" study, he is among 260 men helping researchers find whether selenium delays progression of prostate cancer. The volunteers are randomly prescribed one of four selenium dosages, or a placebo "dummy" pill, and are to be closely monitored for the five years.

"I don't know whether I'm taking the pill or whether I'm taking sugar" says Plattner. "This is my contribution to society."

Through patient interviews, examinations and blood tests measuring PSA -- an indicator of prostate cancer progression -- scientists will document any side effects, good or bad, of prolonged selenium use and any differences in the rate of cancer growth across the five groups.

Selenium decreases prostate cancer rate

Larry Clark, Ph.D., directs the selenium and cancer projects at the University of Arizona Cancer Center. He was in charge of a landmark 10-year study showing the incidence of prostate cancer was 63 percent less among those taking daily selenium supplements.

"We've gone from knowing almost nothing about diet and prostate cancer to prostate cancer being the leading cancer that may be affected by diet, meaning we can do the most to prevent it if we find the right diet," Clark said. He points out that the same study showed selenium users had markedly less lung and colorectal cancer as well. More than a thousand men volunteered for the trial. The study, published in December 1996, caught the attention of many cancer researchers interested in the role diet and nutrition might play in preventing cancer. Suddenly, Clark says, he had company in his selenium research.

"I think it was a surprise for everyone that selenium would have such a major effect on the prostate," he said. Since then scientists have been looking for possible explanations for selenium's apparent good effects. Clark cites a recent report describing a specific type of protein within the prostate that is very responsive to selenium intake. "This probably helps protect against oxidative damage there in the prostate."

Selenium is a trace element found to a varying extent in soil. It enters the human diet through plants such as corn and through the meat of animals grazing on vegetation containing selenium. Products from selenium-rich soils of the Plains and Mountain States carry proportionately more selenium than those coming from the Upper Midwest, Northeast, and Florida, where selenium soil concentration is low. Grains (especially from the Great Plains), fish, organ meats and Brazil nuts tend to be high in selenium. It is often included in broad-spectrum nutritional supplements. There is no official government nutritional guideline on selenium. Typical recommendations range from 70 to 200 micrograms a day.

Holistic urology clinic looks to selenium and beyond

Doctors at Columbia University in New York are also looking into selenium, as well as other nutritional supplements, for preventing and treating prostate cancer. The work is part of the University's Center for Holistic Urology.

A four-year study is under way to see whether a low-fat, high-fiber diet with soy supplementation helps prevent a recurrence of prostate cancer in men who've been treated previously. The study is following 100 men who their cancerous prostates removed surgically but whose cancer was advanced enough at the time of surgery to leave them at higher than average risk of relapse.

Dr. Aaron Katz, director of the center, sees great value in the research. "Currently there is no consensus as to the optimal therapy for those patients who've had radical prostatectomy and who are at high risk for a return of their prostate cancer." Katz favors research that might help reduce dependence on radiation and hormone therapy, which often cause unpleasant or dangerous side effects. "We need more options to treat patients with prostate cancer," he says in a release issued by Columbia Presbyterian Center. "Some patients aren't good candidates for current therapy strategies. Plus recent studies suggest that diet may play an important role in the development and recurrence of prostate cancer."

Katz says he's especially excited by the possibility of treating advanced prostate cancer with a combination of Chinese herbs. In a small study of men who had exhausted all conventional treatments for their cancers, the herbal cocktail called "PC-SPES" brought significant improvement for 85 percent.

Five percent of the subjects developed potentially dangerous blood clots in the legs, leading doctors to prescribe aspirin and other anti-clot medications. Despite the side effects, Katz said, the herbal therapy shows promise as a possible cancer treatment and deserves further study. Laboratory studies attribute a potent anti-cancer effect to PC-SPES in both test tube and animal experiments, he adds.

Katz says details of the study have been accepted for publication in the British Journal of Urology, although many of his colleagues remain unimpressed. "They think it is a bunch of hokeypokey, " he says. "So did I until I started getting into it."

Self-help and supplements still not enough

Those involved in nutritional cancer research say diet supplements should not take the place of regular checkups. The American Cancer Society recommends annual physical examination of the prostate and a PSA blood test starting at age 50. Men with a family history of prostate cancer and others at high risk, including all African- American men, are advised to begin prostate screening at age 45 or earlier depending on individual risk factors.