Gene Therapy Holds Promise for Impotency

Men with damaged nerves after prostate surgery may benefit, researchers say

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By
HealthDay Reporter

TUESDAY, April 29, 2003 (HealthDayNews) -- Researchers think they may have found a way to help men avoid impotence caused by nerve damage, a risk faced by diabetics and those who have their prostate removed.

While they haven't tried their approach on humans yet, the researchers say tests on rats suggest that a type of gene therapy may bring back the ability to have an erection.

The treatment could make prostate removal more tolerable, says study co-author Dr. Michael Chancellor, a professor of urology at the University of Pittsburgh. "Many men are afraid of even screening for prostate cancer. They're afraid of finding it, and they're afraid of the treatment."

The research was reported April 28 at the annual conference of the American Urological Association in Chicago.

While prostate removal is considered the "gold standard" treatment for prostate cancer, many men refuse to have it because of the potential risks of impotency and incontinence, Chancellor says. "They'd rather settle for something else even if there's a higher risk that the cancer may recur," he adds.

An estimated 80 percent of men who have their prostate removed suffer from so-called neuropathic erectile dysfunction.

The problems come during the surgery itself, Chancellor says. "The nerves from the pelvis to the penis travel immediately adjacent to the prostate gland," he explains. "If you just look at them wrong while removing the cancer, the nerves can be cut or partially damaged. Then the men don't get normal erectile function."

Other kinds of prostate cancer treatments, including radiation and cryotherapy (freezing), can also cause impotence by harming nerves, adds Dr. Allan Pantuck, an assistant professor of urology at the University of California at Los Angeles. Potential treatments for the resulting impotency include Viagra, urethral suppositories and direct injections into the penis, he says.

To give the nerves a fighting chance, Chancellor and his colleagues began examining an agent that protects nerves and encourages them to grow. But how could they deliver it to the nerves around the prostate?

In tests on rats with injured nerves, the researchers developed a way to piggyback the agent onto a harmless herpes virus and send it into the prostate region. In some of the rats, the nerves appeared to regenerate after exposure to the agent.

Ideally, the treatment could be given to men before prostate removal or during surgery, Chancellor says. It could also be used on diabetic men.

Pantuck says the findings are promising, but he cautions that the safety of gene therapy is still unclear. He adds the study size is small -- only 11 rats -- and it's hard to tell if the results are statistically significant.

More information

Learn about the disease by visiting the National Prostate Cancer Coalition or the National Cancer Institute.

SOURCES: Michael Chancellor, M.D., director, neurourology, and professor, urology, University of Pittsburgh School of Medicine; Allan Pantuck, M.D., assistant professor, urology, University of California at Los Angeles; April 28, 2003, presentation, American Urological Association annual meeting, Chicago

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