Prostate Cancer Screening - The Screening Controversy

The Screening Controversy

Prostate cancer can develop into a fatal, painful disease, but it can also develop so slowly that it will never cause problems during the man's lifetime. It is difficult for a physician to determine how the cancer will proceed based on screening tests currently available alone.

The United States Preventive Services Task Force (USPSTF) recommended against PSA screening in healthy men finding that the potential risks outweigh the potential benefits. This recommendation, released in October 2011, is based on a review of evidence and concludes that "prostate-specific antigen–based screening results in small or no reduction in prostate cancer–specific mortality and is associated with harms related to subsequent evaluation and treatments, some of which may be unnecessary."

Hal Arkes, a psychologist, presents the statistical case as follows: If there were two auditoriums each filled with 1,000 men, one filled with men who had taken PSA screening tests and the other with men who didn't take the test, there would be just as many men (8) "who died of prostate cancer in each auditorium, which leads us to think in the aggregate it didn't do any good." Among those who took the test there would also be 20 men who were treated for prostate cancers which never would have caused symptoms. Five of these men would have lifelong complications, including impotence and incontinence.

This recommendation has been criticized by many prostate cancer experts for an over-reliance on findings of the U.S. Prostate, Lung, Colon, and Ovarian screening trial. This trial intended to randomize men between screening and no screening. However, because the study was initiated during a time when PSA screening was already becoming widely adopted, there were high rates of PSA testing among men who were in the control arm. This rate of "contamination" was very high: acknowledged by the authors to be 44% before the study started and 52% during the course of study. In fact, the rate was likely much higher, since over 90% of the prostate cancers found in the "control" arm were stage T1 or T2, which by definition can only be detected with screening. The PLCO authors stated in a later publication that the PLCO should not be interpreted as a trial of screening vs. no screening, but rather as a trial of annual screening vs. so-called opportunistic or ad-hoc screening. The USPSTF also based their assessment of the "harms" of screening and treatment based on a biased and out-dated literature review. For just one example, their statement cited a 1:200 risk of dying within 30 days of radical prostatectomy. This number comes from men over the age of 65 treated in the early 1990s; the actual number in contemporary practice is closer to 1:10,000.

PSA testing of men in their mid-70s and older, is discouraged as most people at this age diagnosed with prostate cancer detected by a PSA test would die of other causes before the cancer caused problems. On the other hand, up to 25% of men diagnosed in their 70s or even 80s die of prostate cancer, if they have high-grade (i.e., aggressive) prostate cancer. Conversely, some argue against PSA testing for men who are too young, because too many men would have to be screened to find one cancer, and too many men would have treatment for cancer that would not progress. This argument again ignores the fact that low-risk prostate cancer does not require immediate treatment, but may be amenable to active surveillance.

Prostate cancer is both common (by far the most common solid-organ cancer diagnosed among men and surpassed only by lung cancer as a source of cancer mortality ). Prostate cancer is also extremely heterogeneous: many, perhaps most, prostate cancers are indolent and would never progress to a clinically meaningful stage if left undiagnosed and untreated during a man's lifetime. On the other hand, a subset are potentially lethal, and screening can identify some of these within a window of opportunity for cure Thus the concept of PSA screening is advocated by some as a means of detecting high-risk, potentially lethal prostate cancer, with the understanding that lower-risk disease, if discovered, often does not need treatment and may be amenable to active surveillance.

Screening for prostate cancer is controversial because of cost and uncertain long-term benefits to patients. Testing may lead to overdiagnosis and unnecessary treatment. Follow-up tests can include painful biopsies which can result in excessive bleeding and infection. The discoverer of PSA, Dr. Richard J. Ablin, concludes that the test's popularity "has led to a hugely expensive public health disaster," as only 16 percent of men will ever receive a diagnosis of prostate cancer, but only a 3 percent chance of dying from it. He states that "the test is hardly more effective than a coin toss." Dr. Horan echos that sentiment in his book.

According to the American Urological Association, the controversy over prostate cancer should not surround the test, but rather how test results influence the decision to treat:

"The decision to proceed to prostate biopsy should be based not only on elevated PSA and/or abnormal DRE results, but should take into account multiple factors including free and total PSA, patient age, PSA velocity, PSA density, family history, ethnicity, prior biopsy history and comorbidities.

"A cancer cannot be treated if it is not detected. Not all prostate cancers require immediate treatment; active surveillance, in lieu of immediate treatment, is an option that should be considered for some men. Testing empowers patients and their urologists with the information to make an informed decision."

Private medical institutes, such as the Mayo Clinic, likewise acknowledge that "organizations vary in their recommendations about who should — and who shouldn't — get a PSA screening test." They conclude: "Ultimately, whether you should have a PSA test is something you'll have to decide after discussing it with your doctor, considering your risk factors and weighing your personal preferences."

A study in Europe resulted in only a small decline in death rates and concluded that 48 men would need to be treated to save one life. But of the 47 men who were treated, most would be unable to ever again function sexually and require more frequent trips to the bathroom.

A study by the New England Journal of Medicine found that over a 7 to 10 year period, "screening did not reduce the death rate in men 55 and over." Former screening proponents, including some from Stanford University, have come out against routine testing. In February 2010, the American Cancer Society urged "more caution in using the test." And the American College of Preventive Medicine concluded that "there was insufficient evidence to recommend routine screening."