5 things to know about prostate cancer screening

My husband is a regular guy who avoids doctors like the plague. So when symptoms drove him to his doctor, and he came home with orders to have his prostate checked for cancer, I was concerned. Prostate cancer is the most frequently diagnosed cancer in Canadian men, according to the Canadian Cancer Society. The test he needed was the prostate-specific antigen (PSA) test. PSA is a protein produced by the prostate, the walnut-size gland located behind the pubic bone that surrounds a portion of the urethra, which carries urine from the bladder to the penis. Levels of it can rise when a man has prostate cancer. Here's what you need to know about the PSA test.

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.