PSA Screening

One of the most common questions we are asked during an office visit is whether PSA, or Prostate Specific Antigen, is reliable or worth doing. Certainly, what one sees in the media, and on the internet, does leave one with the impression that PSA is not a good test, and in some ways does more harm than good. The answer we give to this question is yes and no. The reason for this ambiguity is that PSA can be the least predictive screening test that we use in America, or the best. It all comes down to how PSA is used.

Prostate Specific Antigen was developed in the late 80’s, and was introduced as a screening test for prostate cancer and quickly popularized in the early 90’s. Based on a relatively low number of patients studied, a cutoff value of 4.0 ng/dl was determined to be a good point to be used to be determined whether a biopsy would be indicated or not. Thus, PSA was introduced as a test designed to use a single data point to determine relative risk. It must be pointed out that until PSA was discovered, prostate cancer was a disease that almost always was diagnosed during its final stages, after metastasis had occurred. The initial assumption made with PSA was that if we could find prostate cancer at its earliest, embryonic stage, then every one of those patients would avoid a tragic progression of this disease. Thus, when a patient with a minute amount of cancer, even low grade cancer, was found, he was treated aggressively with the idea that his life was being saved. Twenty years of this paradigm generated an enormous amount of data, and these data ultimately revealed this assumption to be untrue.

For the first 20 years of PSA’s usage in American society, many men were unnecessarily biopsied and thus over-treated.

What we learned over time is that although prostate cancer often can be a deadly disease, being the second leading cause of cancer death in men, that the vast majority of prostate cancers found via this manner of PSA screening and aggressive use of prostate biopsy described above are either very slow to grow and metastasize or may not grow at all and simply lay dormant. Thus, in retrospect, that means that for the first 20 years of PSA’s usage in American society, many men were unnecessarily biopsied and thus over-treated. As treatment for prostate cancer will almost always involve temporary or even permanent impact on quality of life, it could be said that PSA did more harm than good to our society in years past.

A group of physicians working for the federal government called the US Preventative Task Force reviewed the data generated by all screening tests in America, including most notably PSA, but also mammogram, colonoscopy and others. They determined the usefulness of a screening test by estimating the number of patients screened or biopsied to save a life. Since that organization, which did not include an Urologist or an Oncologist, performed their work before 2010 and thus was reviewing the data generated by early usage of PSA, it should be no surprise that PSA was the worst performing screening test of them all, with mammograms in women between 40 and 50 also producing similar results. In the era where our government was/is promoting paying for treatments based on “evidence based medicine”, you might remember the first attempt at limiting payment for screening based on this idea when our government considered the performance of mammograms in younger women. It was not soon after that this same report was used as justification for a campaign against PSA screening in America.

Now, Urologists and Primary Care Physicians use PSA as a “trend” test.

However, what was not pointed out clearly is that in large part PSA is no longer used as a single data point test. Now, Urologists and Primary Care Physicians use PSA as a “trend” test. You see, not only has the last twenty years taught us how using a “one size fits all” cutoff is not useful, but we have also learned that prostate cancer can at times simply be followed, that not all prostate cancers are aggressive, and that by far the most likely reason to have a borderline or elevated PSA is the natural and inevitable fact that a man’s prostate grows in a benign fashion as he ages. The fact that PSA screening had not been applied as well as it could have been done in retrospect was not news to Urologists when its poor previous performance was presented to the world; Urologists already had learned a better way to use PSA by shifting its use to that of a “trend test”. This is how we use PSA today, and it is a truly lifesaving test. It is the fact that PSA is utilized far differently and more responsibly than in the past that often makes a patient’s understanding of this test confusing; the description of its use has not caught up to its contemporary application in the media and internet.

If a biopsy was offered to a patient only after two or even three successive rises of the PSA that the ratio of men screened to life saved jumped from among the worst to perhaps the best of all screening tests.

The fact is that at the same time the U.S. Preventative Task Force reports were being used to argue for the cessation of PSA screening in America, very strong evidence-based studies were abundant both in the U.S. and Europe that showed that if a biopsy was offered to a patient only after successive rises of the PSA that the ratio of men screened to life saved jumped from among the worst to perhaps the best of all screening tests. This important point was never part of the federal argument against PSA screening, but was fully ingrained into how Urologists were using PSA. By this time, the goal of PSA screening, based on what we had learned, had already changed radically. The goal now is to find “significant” prostate cancer, not all prostate cancers. Following a PSA trend is the best way to avoid finding “insignificant” or dormant low grade cancer, and Drs. Engel and Losee strictly adhere to this paradigm. Therefore, the old adage that if a man lives long enough he will have prostate cancer may be true, but it is not at all true to say that all men will get “significant” prostate cancer that would go on to metastasis and death if not found. This is what we are looking for and finding today by using PSA as a trend test. This is why PSA screening is now back to being routinely performed. It is not a test subject to guidelines really; it is an art to follow a PSA, and a function of experience on the part of the Urologist to determine when a PSA trend is suspicious for “significant” prostate cancer or not.

If you have an elevated PSA we would be happy to discuss the issue further with you in our office.