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What's New - Prostate Cancer Drug

Kaiser Permanente's Center for Health Research Participates in Federal Study that Finds Drug Prevents Prostate Cancer in Some Men

(PORTLAND, Ore.) - Men who took a drug that affects male hormones reduced their chances of getting prostate cancer by nearly 25 percent compared with men who took a placebo, according to the results of a federal study released online on June 24 by the New England Journal of Medicine. 

Kaiser Permanente's Center for Health Research studied 39 men in the Portland-Vancouver area as part of the National Cancer Institute's Prostate Cancer Prevention Trial (PCPT). Nationally, nearly 19,000 men took part in the study at 220 study sites around the country over the past decade, making this the largest, longest prostate cancer prevention study ever conducted in the United States. Other Oregon sites included Oregon Health & Science University's Cancer Institute with 299 participants, and Providence Health System with 250.

According to Andrew Glass, MD, principal investigator for the study at Kaiser Permanente's Center for Health Research, "This study is the first to indicate that prostate cancer, a common and serious disease in men, may be prevented by a simple, daily medication that is also free of serious side effects. It is the initial step in an important process to prevent prostate cancer and will surely be followed by other advances"

Although study participants taking the drug, known as finasteride, had fewer cancers overall, they had a greater number of high-grade prostate cancers, according to Andrew Glass, MD, the principal investigator for the study at CHR. In the entire group of men taking finasteride who were evaluated, 6.4 percent had high-grade cancers compared to 5.1 percent of men evaluated in the placebo group.

Researchers are studying several possibilities to explain why some men on finasteride had more high-grade tumors. Dr. Glass says the drug may affect the appearance of prostate cancer cells, and this may lead to a false estimate of tumor grade, which is determined visually by a pathologist. Or finasteride may allow more aggressive tumors to develop, either by preventing only low-grade tumors, or by making the prostate gland more favorable to aggressive tumors.

Men's most common malignancy

Prostate cancer is the most common malignancy among men and the second leading cause of cancer death in men in the United States. Overall, roughly one in six American men will develop prostate cancer during his lifetime - a greater percentage than women who will develop breast cancer over a lifetime. The American Cancer Society (ACS) estimates that 3,200 men in Oregon and 3,900 men in Washington will be diagnosed with prostate cancer in 2003. More than 220,900 men will be diagnosed nationwide. Four hundred men in Oregon, 500 men in Washington and 28,900 men across the nation will die of the disease in 2003, the ACS says.

Men chosen for the study showed no evidence of prostate cancer at the start of the trial, according to Dr. Glass. To enter the study, men needed to have a normal digital rectal exam and a prostate specific antigen (PSA) level of 3 ng/ml or less. These tests were repeated annually.

Study participants were randomly divided into two groups. Half took one 5 mg tablet of finasteride per day for seven years. The other half took a placebo, which is an inactive pill that looks like finasteride. Neither the participants nor the study physicians knew which men were getting finasteride and which men were getting placebo. The trial design, called "double-blinding," permits researchers to see the possible benefits and side effects of finasteride without being influenced by other factors, such as the expectations of participants or researchers.

The participants also agreed to have a prostate biopsy after they had participated for seven years. At the time the trial ended, about 9,000 men had undergone biopsies.

Study drug approved in 1992 for prostate enlargement

The FDA approved finasteride in 1992 for the treatment of benign prostatic hyperplasia (BPH), a noncancerous enlargement of the prostate gland. Because BPH and prostate cancer are influenced by similar hormonal factors, researchers believed the drug might also prevent cancer. Finasteride controls BPH by reducing levels of the hormone dihydrotestosterone (DHT) in the prostate. The drug works by blocking the activity of an enzyme that converts testosterone, the primary male hormone, to DHT.

The study was coordinated by a network of researchers called the Southwest Oncology Group (SWOG) and funded by the National Cancer Institute (NCI). Another large prevention study currently under way, the Selenium and Vitamin E Cancer Prevention Trial (SELECT), also being coordinated by SWOG, is available to men in the Portland-Vancouver area. For more information on PCPT or SELECT, the public may call the NCI's Cancer Information Service at 1 800-4-CANCER (1 800 422-6237) for information in English and Spanish. Or visit www.cancer.gov/pcpt on the Web.

For more infomation contact:
Terry Fitzpatrick (503) 335-6602 or
Jim Gersbach (503) 831-4820

Released: June 24, 2003