The Truth about PSA testing
LAURENCE KLOTZ, Globe and Mail Sept. 15, 2004

A pioneer of the PSA prostate cancer test now questions its worth. The subsequent headlines regarding the test's limitations drew attention to an important controversy in men's health. But they raised more questions than they answered and may have caused unnecessary alarm for men who have already had this test and underwent treatment. Some clarification is in order.

Cancer development begins at birth. As sources multiply and divide, we develop sequential mutations that eventually result in areas that look abnormal under the microscope and are called "cancer" by the pathologist. In the prostate, these begin to appear in the 30s, and are present in most men by their 70s. Usually, they remain microscopic and don't pose a serious health threat. In some men, however, these cancers acquire the ability to invade and spread.

About one in three men over 50 harbour these tiny areas that look like cancer, and about one in 30 will develop spread of the disease and die. Prostate cancer is still the second most common cause of cancer death next to lung cancer.

Until recently, it was thought that the PSA (prostate-specific antigen) became elevated as a result of the development of the larger volume of cancer. The recent data by Stanford's Thomas Stamey (the PSA pioneer) have demonstrated that, for mildly elevated PSA, this is not true. But that doesn't mean the test is worthless. It still works in many respects.

A rapid rise in PSA has been clearly demonstrated to be associated with aggressive prostate cancer. Furthermore, by the time someone developed advanced prostate cancer, the PSA is almost always very high. The widespread use of PSA testing has resulted in the disease being diagnosed at a stage when it is much more curable. More important, death from prostate cancer has dropped 25 per cent in the past years in North America. This advance deserves as large a headline as the one casting suspicion on the PSA test.

Men with high-grade cancer or cancer that is quite extensive should be treated aggressively, with surgery or radiation. The majority, with small volume cancer on the biopsy and low grade, should be watched carefully. If their PSA rises rapidly once they have been identified as having low-grade cancer, they should be moved to aggressive treatment.

This approach, which we have been using at Sunnybrook and Women's College Health Sciences Centre since 1995, yields terrific results. Two-thirds of the patients have avoided radical surgery or radiation altogether, one-third have been treated after a period of observation, and most of them have been cured.

The prostate cancer survival rate, with almost 10 years of follow-up, is 99.5 per cent, PSA testing has resulted in prostate cancer being diagnosed at a much more curable stage, but has also resulted in many more men with non-life-threatening cancer being diagnosed. To stop PSA testing will result in the majority of men with potentially curable disease being diagnosed too late The solution is to continue to encourage men to have the test done, but to be much more selective about who is treated.

Laurence Klotz is a professor of surgery at the University of Toronto and head of the Prostate Cancer Group at Sunnybrook and Women's College Health Sciences Centre.