New research suggests that Avodart, a drug used to treat an enlarged prostate gland, may help slow the progression of early stage prostate cancer, reducing the need for aggressive treatment in some men.

Prostate cancer can grow and spread slowly, which is why some men are urged to engage in so-called watchful waiting when the cancer is first diagnosed. Avodart (dutasteride) may help such men feel comfortable with surveillance as opposed to radical treatment, the researchers noted.

“The concept of active surveillance is gaining traction in most parts of the world,” said study author Dr. Neil E. Fleshner, head of the division of urology at the Princess Margaret Hospital in Toronto. Still, some men are uncomfortable with doing nothing in the face of a cancer diagnosis, he said. “By using this drug, we can improve the proportion of men who remain committed to the surveillance.”

The findings are published online Jan. 25 in The Lancet.

According to the U.S. National Cancer Institute, one out of every six men in the United States will develop prostate cancer in his lifetime. But because many of those cancers are low-grade, most will die of something else.

Avodart belongs to a class of drugs called 5-alpha reductase inhibitors. These drugs work by interfering with the effects of certain male hormones on the prostate. In the three-year study, prostate cancer progressed in 38 percent of 144 men with early prostate cancer who were treated with Avodart and 48 percent of the 145 men who received a placebo.

Men seem less anxious about the cancer diagnosis when they are doing something more proactive, Fleshner said. “The drug augments active surveillance and avoids most of the side effects associated with surgery and radiation,” he said. Prostate removal surgery and/or radiation can lead to impotence and incontinence, he said.

The medication does have side effects, however, including reversible breast enlargement and tenderness and some sexual dysfunction.

“We know that we are over-treating prostate cancer,” said Dr. Louis Potters, chairman of radiation medicine at North Shore University Hospital and Long Island Jewish Medical Center in Manhasset, N.Y.

“In the U.S., patients have a tendency to hear the word ‘cancer,’ and want to treat it right away,” he said. “In these men with early prostate cancer, we can now say, ‘Let’s put you on this medication, and see what happens over the next couple of months.’”

However, some experts have concerns about 5-alpha reductase inhibitors. The U.S. Food and Drug Administration recently issued a warning that men who take these drugs to treat enlarged prostate glands may be at increased risk for high-grade prostate cancer.

Dr. Ryan Terlecki, an assistant professor of urology at Wake Forest Baptist Medical Center in Winston-Salem, N.C., said this may dampen enthusiasm for use of the drug to treat cancer.

“The overall role that these medications will play for urologists will decrease,” Terlecki said. Doctors will likely begin looking toward noninvasive and/or non-medical treatments such as the use of thermal heat to cope with some of the symptoms of prostate conditions, he added.

More information

Learn more about prostate cancer at the American Cancer Society.

SOURCES: Neil E. Fleshner, M.D., head, division of urology, Princess Margaret Hospital, Toronto; Louis Potters, M.D., chairman, radiation medicine, North Shore University Hospital and LIJ Medical Center, Manhasset, N.Y.; Ryan Terlecki, M.D., assistant professor, urology, Wake Forest University, Winston-Salem, N.C.; Jan. 25, 2012, The Lancet, online

Last Updated: Jan. 24, 2012