Regular PSA tests from age 35 necessary to track speed of change from year to year

July 15, 2004 --The rate at which prostate-specific-antigens (PSA) levels rise may be more important for predicting the danger of prostate cancer than the PSA levels themselves.

In findings published in the July 8 issue of The New England Journal of Medicine, investigators at four centers analyzed PSA levels in men and found, for the first time, that a larger PSA increase in the year before radical prostatectomy signaled more aggressive forms of the cancer.

Patients experiencing a large one-year rise died at a higher rate within seven years despite having their cancerous prostates removed.

These results offer evidence that monitoring the rate of PSA changes over time --" PSA velocity" -- will help physicians assess the risk of prostate cancer death.

Currently, physicians and patients face a dilemma when prostate cancer is detected, because it is difficult to predict whether the cancer will grow slowly and harmlessly, or turn aggressive and life-threatening. This had led some experts to call for new tests to replace the PSA test.

Prostate cancer, the second most common cancer in men, causes some 29,000 deaths a year in the United States, according to the American Cancer Society. Currently, PSA testing -- a simple blood exam performed during a routine visit with a primary care physician -- helps indicate presence of the disease. However, no consensus exists on how to gauge the likelihood or potency of prostate cancer simply from PSA levels.

This lack of clarity results in many patients undergoing "watchful waiting," in which prostate cancer is monitored but not treated until PSA levels reach a certain point. The new study demonstrates that by measuring changes in PSA from year to year, caregivers can better determine whether watchful waiting is appropriate.

"This study provides solid evidence that PSA testing over a period of time is a reliable indicator of possible risk of death from prostate cancer," states the study's lead author, Anthony D'Amico, MD, PhD, a radiation oncologist with Dana Farber Cancer Institute and Brigham Young Hospital. "We hope these results will encourage physicians to measure 'baseline' PSA levels of patients at age 35, then monitor them through their 40s to determine risk and appropriate treatment if the cancer appears. As with a mammogram, this test should be done yearly to catch the disease when it is curable."

In this study, D'Amico and his colleagues analyzed PSA data from 1,095 men, all of whom were approximately 65 years old and had undergone a radical prostatectomy. The data were provided from a screening study conducted at Northwestern University Feinberg School of Medicine. Measurements of prostate-specific-antigen were taken every six to 12 months, along with digital rectal exams before surgery. Within this group, researchers found that 61 percent of all deaths were due to prostate cancer when the PSA level had risen at least two points during the year before diagnosis.

Overall, the risk of cancer death was about 10-fold higher in men whose PSA numbers rose by more than two points in the year before diagnosis, versus those whose levels rose two points or less during that period.

The bottom line, D'Amico says, is that "It is not the level of PSA that is important but rather the change from year to year."

"The information provides physicians with a call to action to evaluate PSA results year-to-year," he adds.

"In addition, while watchful waiting is often recommended when the risks of treatment are thought to outweigh the benefits, knowledge of how to best interpret historical PSA levels will identify if the disease is aggressive or not. This will give patients and their physicians the insight needed to select the appropriate treatment."

Also contributing to the study were investigators from the University of Connecticut, Northwestern University, and Washington University in St. Louis.

Dana-Farber Cancer Institute is a teaching hospital linked to Harvard Medical School. It is one of the leading cancer research and care centers in the United States. It is recognized as comprehensive cancer center by the National Cancer Institute.

Dana Farber cancer patient care » prostate cancer

For more about tests to detect prostate cancer see our PSA information pages.