NEW YORK, May 21 (UPI) -- Re-analysis of a drug trial found finasteride reduces prostate cancer risk without boosting the odds of aggressive tumors, U.S. researchers said.

The re-analysis of the Prostate Cancer Prevention Trial was conducted by the New York-Presbyterian Hospital/Weill Cornell Medical Center/Weill Cornell Medical College.

The trial, which involved more than 18,000 men age 55 or over, stopped in June 2003 because researchers noted that while the drug reduced prostate cancer in men taking finasteride by up to 25 percent, men taking finasteride also appeared to have more aggressive tumors if and when they developed prostate cancer.

Some experts worried that finasteride was encouraging higher-grade cancers, but the re-analysis found that worry should be laid to rest, the researchers said.

"Finasteride has long been used by doctors to treat benign enlarged prostate -- it shrinks the prostate," lead author Dr. Steven A. Kaplan, a urologist at New York-Presbyterian Hospital/Weill Cornell Medical Center, said in a statement.

"So when we accounted for this shrinkage in prostate volume, the disparity in tumor aggressiveness between the finasteride and placebo groups vanished."

The findings were presented at the annual meeting of the American Urological Association, in Orlando, Fla.