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Health Science Center urologist in lead as U.S. announces finasteride reduces risk of prostate cancer 25 percent

Thompson Photo San Antonio (June 26, 2003) — "I am firmly convinced that this is the first step in conquering prostate cancer." That's the message from Ian M. Thompson, M.D., professor of surgery and chief of urology at The University of Texas Health Science Center at San Antonio (UTHSC), who today announced results of a nationwide, seven-year study of the drug finasteride to determine whether it decreased the risk of prostate cancer in men over 55. The findings will be published online Thursday in the New England Journal of Medicine.

The Prostate Cancer Prevention Trial (PCPT) is being stopped more than a year early because researchers headed by Dr. Thompson saw a 24.6 percent reduction in cases of prostate cancer when they compared men treated with finasteride and men who received a placebo. They concluded that the drug prevents or delays the appearance of prostate cancer, although sexual side effects and tumors of a higher grade were more common in the finasteride group. About 200,000 U.S. men are diagnosed with prostate cancer annually, so finasteride might prevent 50,000 cases.

"This is really a landmark study," Dr. Thompson said in his office at UTHSC. "Imagine — more than a decade ago when the study was envisioned, the words 'prevention' and 'prostate cancer' were never found in the medical literature. When we went to Bethesda, Maryland, (home of the National Institutes of Health) to discuss the concept, we were moving into uncharted territory."

The design of the study took about a year and was one of the most challenging aspects, primarily as the researchers looked at how finasteride affected PSA — the method used to detect prostate cancer (it lowers PSA). "We also didn't know if healthy men would take a pill daily for seven years," Dr. Thompson said. "We were tremendously impressed by the interest of men across the nation. The interest was enormous and more than half of all of the participants enrolled in the first year of the study. Ultimately, during our three-year enrollment period, 18,882 men enrolled."

The PCPT results are encouraging. "Until now, the only way men could address their concern about prostate cancer was through early detection and treatment. With a man's lifetime risk being 16.67 percent, the impact is enormous. Our study suggests that the risk can be reduced by 25 percent with finasteride use," Dr. Thompson noted.

Charles A. Coltman Jr., M.D., president and CEO of San Antonio's Cancer Therapy and Research Center, collaborated on the study in his role as chairman of the Southwest Oncology Group (SWOG), which has its operations office in San Antonio. The other journal co-authors are from the SWOG Statistical Center in Seattle; the University of Colorado, Denver; the National Cancer Institute; the Mayo Clinic; Wilford Hall Medical Center, San Antonio; Southeastern Medical Oncology Center, Goldsboro, N.C.; The University of Texas M.D. Anderson Cancer Center, Houston; and Grand Rapids Community Clinical Oncology Program, Grand Rapids, Mich.

Although fewer men on finasteride developed cancer, those who did ran a greater risk of having a more-serious cancer than the men who developed cancer in the placebo group. "We don't know if the increase in higher-grade tumors was 'real' or not," Dr. Thompson said. "Previous studies have suggested that tumors diagnosed in men on hormonal therapy appear to be higher grade when they really are not. If we assume, however, that the increase was correct, the magnitude of the increase in higher-grade tumors was still much less than the reduction in overall cancers."

UTHSC has one of the nation's strongest prostate cancer research programs, headed by Dr. Thompson. Projects include the SABOR project (San Antonio Biomarkers of Risk for Prostate Cancer), which continues its drive to enroll 10,000 Hispanic, African-American and white men to sift out genetic determinants of prostate cancer. SABOR has enrolled 2,000 men and has 40 percent minority enrollment — much higher than other large-scale prostate cancer studies have achieved.

"Our goal is to help do a better job in detecting prostate cancer," Dr. Thompson said. "Our research program is designed to identify those men who are at risk of cancer, so that they can be counseled about options to prevent the disease. We want to identify those for whom prevention strategies work, discover better blood tests for the disease, and ultimately, reduce the risk of complications and need for treatment for prostate cancer."

Contact: Lucie Portela or Aileen Salinas