1. Three main conditions can elevate levels of PSA:
•cancer of the prostate;
•an enlarged prostate (a normal condition of aging that causes symptoms such as a frequent need to urinate, especially at night, as the enlarging prostate presses against the urethra); and
•an inflamed prostate, the most common cause of which is a bacterial infection (again, the prostate presses against the urethra).
These last two conditions are benign (not serious) and respond well to drug therapy.
2. A normal PSA result doesn't necessarily mean you don't have prostate cancer.
PSA levels are measured in nanograms per millilitre (ng/mL). Evidence gathered since the clinical application of the PSA test was first described in 1987 suggests that a measurement of 4 ng/mL or more indicates the possible presence of cancer.
However, a recent study published in The New England Journal of Medicine shows that a level under 4 ng/mL doesn't rule out cancer in all men. That study, which included almost 19,000 men, found that PSA tests missed 15 per cent of prostate cancers in a subset of men who had normal PSA levels (that is, under 4 ng/mL) during the seven-year study.
“What this study is saying is that we need better tests to identify which prostate cancers are lethal as opposed to the ones you don't die from,” says Dr. Robert Nam, assistant professor of surgery at Sunnybrook and Women's College Health Sciences Centre in Toronto. Nam is coauthor of So You're Having Prostate Surgery: What Happens Next? (John Wiley & Sons, 2003, $22.95).
Another recent study by researchers at Brigham and Women's Hospital in Boston seems to suggest that the speed with which PSA levels rise in the year prior to prostate cancer being diagnosed is a better indicator of how lethal the cancer is than the actual level.
3. Although not perfect, a biopsy of the prostate (during which a tiny amount of tissue is removed with a needle for examination) is still the most reliable test for prostate cancer.
The tissue taken during a biopsy can be examined under a microscope for malignant cells, thus providing direct evidence of the presence of prostate cancer. In contrast, symptoms such as problems urinating are a much less reliable indicator of prostate cancer since this type of cancer doesn't often cause symptoms in the early stages. It's usually only when the cancer grows to the point of blocking the urinary tract that symptoms develop.
Urinary symptoms don't necessarily mean advanced cancer. As the prostate grows with age, it will begin to cause chronic problems with urination, and the same happens when the prostate becomes inflamed, usually because of a bacterial infection. So if a man has urinary symptoms and his PSA is high, he's more likely to have a benign condition than cancer, says Nam. (My husband had a bacterial infection, and it was this discomfort that drove him to the doctor in the first place.)
While biopsies are our best indicator of the presence of cancer, they're not perfect. Since cancers are usually microscopic, it's often difficult for urologists to identify them. It's also difficult for doctors to find abnormal areas in the prostate by ultrasound if they do exist; biopsies are often obtained in a “random pattern” in areas of the prostate where cancer is most likely to grow, and so there may be abnormal areas, but the sample may not contain them. “There is up to a 25 per cent false negative rate on biopsy [which means cancer is present, but the biopsy missed sampling the cancerous tissue],” says Nam. If a man's PSA level remains high but he has no symptoms, he may have to undergo a second biopsy.
4. There is no agreement among specialists on routine PSA testing for men over the age of 50.
There are essentially two general camps: on the one side are those who believe that PSA screening might save lives (almost 90 per cent of men are still alive five years after being diagnosed with prostate cancer according to research from the Canadian Cancer Society); and on the other side are those who maintain that screening can lead to invasive medical tests and possibly the removal of a prostate gland to treat a slow-growing cancer that probably never would have been fatal or even caused symptoms had it been left intact.
The Canadian Cancer Society recommends that men over the age of 50 discuss the risks and benefits of early detection with their doctor, leaving it up to the individual to decide if he wants the PSA test or not. The Canadian Task Force on the Periodic Health Examination is not in favour of the PSA test for men over the age of 50.
For their part, the American Urological Association and the American Cancer Society recommend that men undergo PSA screening starting at age 50. This position is shared by many Canadian urologists who work with prostate cancer patients, patients who survived prostate cancer because of timely detection with PSA testing, and the Prostate Cancer Research Foundation of Canada.
As for Nam, he is in favour of PSA screening for men over 50 “who have at least 10 years of life expectancy” and for those men over the age of 40 whose brothers, uncles or father had prostate cancer (they're two to eight times more likely to develop prostate cancer themselves).
5. You may have to pay for a PSA screening test.
Men who want the PSA test may have to pay for it themselves if it's not covered by their provincial health insurance. However, some institutions (Sunnybrook and Women's College Health Sciences Centre in Toronto, for example) offer free PSA tests. Check with your local hospital to see if the test is covered or what the cost is.