May 21 (HealthDay News) -- Men who keep their cholesterol down might also help lower their levels of prostate specific antigen, a protein that can warn of prostate cancer, a new study says.

"Prostate cancer is controlled by the male hormone testosterone. The main molecule that forms testosterone is cholesterol," said Dr. Murugesan Manoharan, an associate professor of urology at the University of Miami Sylvester Comprehensive Cancer Center, who was not involved in the study. "So it is known that prostate cancer is related to testosterone, and testosterone is related to cholesterol."

The study's inference is that by lowering cholesterol, you also lower PSA, which in turn may reduce the risk of prostate cancer, Manoharan said. "Obviously this is a very small study and does not confirm anything, but it is a very good start that could lead to something more at a later point," he said.

The results of the study were expected to be presented Wednesday at the American Urological Association annual meeting, in Orlando, Fla.

For the study, researchers collected data on 1,214 men taking cholesterol-lowering drugs called statins. The researchers found that PSA levels were lower after starting the statins, and the drop in PSA was proportional to the drop in cholesterol.

The results of the study confirm those of a previous study that also found that lowering cholesterol lowered PSA, the researchers noted. If confirmed, the results of the new study would provide more evidence that cholesterol plays a role in the biology of the prostate, the researchers said.

It's still not clear, however, whether lowering PSA with cholesterol-lowering drugs may actually hide developing prostate cancer, Manoharan said.

"Bringing down the PSA levels artificially does not mean necessarily decreasing the chance of developing prostate cancer," he said. "It might just bring the blood test reading down without reducing the risk of prostate cancer. In fact, we could miss the prostate cancer, because the PSA readings are on the lower side."

Manoharan said the new findings need to be studied further. "If statins do, in fact, reduce the incidence of prostate cancer that would be a very good thing," he said.

Two other studies presented Wednesday confirmed that so-called "watchful waiting" of men with a low risk of prostate cancer is a viable option. Watchful waiting is a strategy in which no treatment is given, but the patient is monitored to check the progress of the cancer.

But, the researchers of one of the studies noted that PSA exams and digital rectal exams aren't good predictors of the progress of prostate cancer. They suggest that better monitors of the disease need to be developed.

In another study presented Wednesday, researchers from Johns Hopkins University found that men 75 to 80 years of age with low PSA levels -- less than 3 nanograms per milliliter of blood -- may be able to stop regular prostate cancer screenings.

The researchers found that these older men who have PSA levels below 3 nanograms per milliliter have a low probability of dying from prostate cancer, while men with PSA levels of 3 nanograms or more have an increased risk of dying from the disease.

SOURCES: Murugesan Manoharan, M.D., associate professor of urology, University of Miami Sylvester Comprehensive Cancer Center; May 21, 2008, presentation, American Urological Association annual meeting, Orlando, Fla.