Dutasteride

2 efforts emerge to further prostate cancer fight

By MARILYNN MARCHIONE mmarchione@journalsentinel.com, Journal Sentinel

Monday, October 20, 2003

Recent news that a drug can lower a man's risk of getting prostate cancer has boosted hopes for two other large prevention studies, one involving a similar drug and the other, a vitamin-dietary supplement combination.

Doctors in Wisconsin are signing up men for both studies, which are aimed at preventing the second most common cancer and cause of cancer deaths in men.

For men and their doctors, this disease is a real dilemma. Many prostate tumors are slow-growing and never really threaten a man's health. Others prove fatal. And there's no good way to predict how the disease will behave in which patients, making treatment decisions agonizingly difficult.

It would be much better to find something that could prevent tumors from developing in the first place, especially for men at high risk of prostate cancer, such as African-Americans and men with a family history of the disease.

Excitement about this possibility rose in June, when a government- funded study of 19,000 men was stopped early, after it became clear that those taking the drug finasteride had a 25% lower risk of developing prostate cancer.

The drug, sold as Proscar for enlarged prostates and at a smaller dose as Propecia for baldness, shrinks the prostate and lowers testosterone, a hormone that causes the prostate to enlarge and promotes the growth of cancer.

Similar study launched

"The finasteride study was very encouraging," said Barry Usow, a Milwaukee urologist who is participating in a newly launched study of a similar drug -- dutasteride, sold as Avodart.

Like finasteride, dutasteride is approved for use against benign enlargement of the prostate and also may promote hair growth.

Its maker, GlaxoSmithKline, will enroll 8,000 men in the study worldwide, half in the United States. Eight doctors at the Clinic of Urology with offices at St. Luke's Medical Center, on Layton Ave. in St. Francis, and on Rawson Ave. in Franklin, are enrolling participants.

Participants will need to make nine free clinic visits during the four-year study and will be randomly assigned to get either the drug or dummy pills without them or their doctors knowing which they got until the study is over.

Men must be 50 to 75 years old, have benign enlargement of the prostate and must have had a biopsy to check for prostate cancer within the last six months that was negative.

With the biopsy, "you're going to eliminate those patients who might have had early cancers" that were undetected at the time they enrolled in the study and that could have biased results -- a potential problem with the finasteride trial, Usow said.

Additional biopsies will be done at two and four years to see if differences in cancer rates can be seen.

Some doctors think dutasteride might be even better at preventing prostate cancer because it blocks two enzymes that convert testosterone, while finasteride blocks one.

"It's possible that it will be more effective than finasteride," but it also might have unforeseen drawbacks that won't be known until it's tested, said Eric Klein, chief of urologic cancers at the Cleveland Clinic Foundation.

He is not involved in the dutasteride study but leads another large prostate cancer prevention experiment -- SELECT, the selenium and vitamin E trial, funded by the National Cancer Institute.

'Surprising' result

It seeks to determine whether the nutrient selenium and vitamin E alone or in combination can prevent prostate cancer. Some small preliminary research suggests it might, but the studies weren't for prostate cancer. One tested selenium against skin cancer. It didn't prevent that disease, but researchers noticed that male participants had lower prostate cancer rates.

"It was a surprising and unexpected result" that warrants further testing, Klein said. There also are biological explanations for how these two substances -- which are anti-oxidants, substances that help repair damage to DNA -- might prevent cancer.

"The science behind SELECT is very solid, along with the epidemiology," so there's a lot of reason to hope it will work, Klein said.

The University of Wisconsin Comprehensive Cancer Center, the Marshfield Clinic, the Medical College of Wisconsin in Wauwatosa, Aurora Sinai Medical Center, Oconomowoc and Waukesha Memorial Hospitals' Regional Cancer Centers and the UW Cancer Center at Wausau Hospital are among the 400 participating sites in the U.S. and Canada.

Eligibility criteria are similar to those in the dutasteride trial -- African-American participants must be older than 50, whites must be over 55, and men can have no evidence of prostate cancer.

The study began in July 2001 with a goal of enrolling 32,400 participants in five years and already has almost 26,000 and should finish up to a year ahead of time, Klein said. It's been surprisingly easy to recruit for these prevention studies, he said.

That's a testimony to how eager men and their doctors are to find something that will prevent this common and vexing cancer.

For more information on the dutasteride trial in Milwaukee, call (414) 482-0498. For more information about SELECT or prostate cancer call the National Cancer Institute's Cancer Information Service at (800) 422-6237 or visit: www.cancer.gov/clinicaltrials.

PROSTATE CANCER FACTS

Prostate cancer is the second most common cancer in males after skin cancer and the second leading cause of cancer deaths in men.

Incidence: About 220,900 new cases will be diagnosed this year.

Deaths: About 28,900 American men will die of it in 2003.

Screening: Experts recommend men over 50 have an annual digital rectal exam and consider having a PSA blood test.

Prevention: Studies under way are testing the drug dutasteride and a combination of vitamin E and the nutrient selenium as possible prevention measures.

Sources: National Cancer Institute, American Cancer Society

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