Mayo Clinic Research Helps Identify Men at Risk for Recurring Prostate Cancer

Tuesday, June 12, 2001

ROCHESTER, MINN. — In the most comprehensive study of its kind to date, Mayo Clinic urologists have found that a simple blood test is the single most important predictor to determine which men are most likely to experience recurrence after undergoing surgery for prostate cancer.

The predictor is called prostate-specific antigen (PSA) doubling time. PSA is produced in the prostate gland and can be measured by a blood test.

In men whose PSA levels increased quickly — doubling in six months or less — 62 percent developed cancer recurrence. Cancer recurred in only 13 percent of men with a calculated PSA doubling time of ten years or more.

For those whose calculated PSA doubling time was 10 years or longer, 87 percent were cancer free in five years. A substantial number of men in the study had prolonged PSA doubling times so the distinction is important information for patient and physician.

"We confirmed that the presence of PSA after surgery doesn't always mean that prostate cancer will progress rapidly and this should lessen anxiety felt by the patient," says Dr. Blute.

Men with PSA doubling times of six months or less now have a good indication that additional treatment may be beneficial. Men with slower rates may want to take a wait-and-see approach or participate in clinical trials with less aggressive treatment options.

The study is published in this month's edition of Mayo Clinic Proceedings.

"This study provides solid information to help patients and their doctors make informed decisions about care after surgery," says Michael Blute, M.D., a Mayo Clinic urologist and lead investigator on the study.

Prostate cancer is the most common cancer in American men. It's estimated by age 50, up to one in four men have some cancerous cells in the prostate gland. Each year, 38,000 United States men die due to prostate cancer.

Surgery to remove the prostate gland, called radical prostatectomy, cures most men. An absence of PSA after surgery is the best indicator that the cancer is gone.

But, in about one-third of the men, PSA levels increase after surgery. "It's a major source of concern because no major studies have conclusively demonstrated the best treatment options for these men," says Dr. Blute.

Men at risk of recurrence usually are treated with radiation or hormone therapy. Both can have significant side effects and affect the quality of life. Radiation can cause nausea, hair loss and loss of energy. Hormone therapy can cause muscle weakness, loss of libido and increased risk of osteoporosis.

"This study was designed to learn more about the significance of PSA levels," says Dr. Blute. "We wanted to better determine which men needed continued, aggressive treatment after surgery," says Dr. Blute.

Researchers analyzed the medical records of 2,809 men who had radical prostatectomies at Mayo Clinic from 1989 to 1993. As expected, about one-third of the men showed increasing PSA levels after surgery.

Other researchers have looked at PSA doubling time as a predictor of cancer. This study is the largest single study of men treated by surgery and followed until cancer recurred.

Mayo Clinic Proceedings is a peer-reviewed and indexed general internal medicine journal, published for 75 years by Mayo Foundation, with a circulation of 130,000 nationally and internationally.

Contact: Chris Gade 507-284-5005 (days) 507-284-2511 (evenings) e-mail: newsbureau@mayo.edu

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