The purpose of this section is to help you in discussing the PSA test with your male patients. The term "screening" is defined here as performing a stand-alone PSA test to look for prostate cancer in asymptomatic men who have no physical abnormality suggesting the presence of prostate cancer (or who have only mild symptoms of prostatism, which are present in virtually all men over the age of 50).

Routine screening for prostate cancer is controversial for a number of reasons.

Much of the disagreement involves quality of life issues. Those against routine screening argue that given the possibility of unnecessary significant morbidity associated with the diagnosis and treatment of prostatic cancer lesions, careful evaluation of screening is imperative; those in favour argue that early detection strategies may be found to save lives.

Ideally, a screening test should be capable of distinguishing between cancers or precancerous lesions that, when left undetected, result in morbidity and mortality-and cancers that do not. The problem with the PSA test is that it is not perfectly accurate; it lacks sensitivity¹ and specificity². In the context of screening, it can be difficult to interpret exactly what an elevated PSA means: it can be elevated in benign prostatic hyperplasia (BPH), in less aggressive-appearing, low-grade tumours, as well as in rapidly-growing tumours, or because of day-to-day variation (see Section IV).

1. The proportion of truly diseased persons in the screened population who are identified as diseased by the screening test.

2. The proportion of truly non-diseased persons who are identified correctly by the screening test.

Prostate cancer differs from other types of cancer in that its clinical course can vary widely. In some men, prostate cancers can be slow-growing, non-life-threatening, may not become clinically apparent during their lifetime, and may never require treatment. However, in others the diagnosis is made only when the cancer is too advanced to cure. The difficulty comes in differentiating between relatively benign disease and a course that may prove fatal, which reflects the diversity of the natural history of the disease. Usually the treatment of advanced prostate cancers is beneficial, but the current treatments have not yet been adequately or completely evaluated to demonstrate whether they can extend life in men with early stage or low grade prostate cancer (see Appendix A). Furthermore, these treatments have the potential for significant adverse events, and patients with early-stage prostate cancer who are treated with surgery or radiation are exposed to the same risk of significant side effects as are patients with later-stage disease: incontinence, erectile dysfunction (impotence), rectal injury and operative mortality. Whether or not prostate cancer is diagnosed early, the majority of men who have the disease will not experience significant symptoms and will in fact die from another cause. Autopsy studies have shown that by the age of 90, most men have latent or microscopic prostate cancer, which has not been the cause of death.

All these statements obviously are of concern to physicians trying to help men decide about the uncertain benefits of undergoing prostate cancer screening. They also highlight why family doctors should assist men to understand and evaluate the potential risks and harms, as well as the potential benefits, that may result from the process that is put into motion by screening. This process may continue on through diagnosis and treatment with its resulting side effects. Long-term randomized controlled trials (RCTs) providing the evidence to determine whether screening and treatment of early stage disease are beneficial will take about 15 years to complete.

In order for doctors to be able to help their male patients make a decision about whether or not they should have a PSA test for screening, both doctor and patient need to be well informed. The role of the family doctor here is twofold: to help men gain the information they need to understand the implications of PSA testing; and, for those who choose to be tested, to exercise clinical judgement and to assist with proper interpretation of the results, given the test limitations.

Men between the ages of 50 and 75 years who have a life expectancy of at least ten years (meaning the absence of severe chronic health conditions) should be offered a brochure that discusses the potential benefits and risks of screening with PSA testing (available from the Canadian Cancer Society). For men who have a family history of prostate cancer or other factors that put them at high risk (e.g., black race), this information should be provided after the age of 40.

The Ontario Ministry of Health supports the expert committee's recommendation that men be informed of the risks and benefits of PSA testing before they decide whether they should undergo it. Men should be able to make an informed decision, with the help of their family physician, as to what is best for them as individuals.

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