Screening for Prostate Cancer- PSA Testing or Not??


PSA-Test11In an official move that should have come as no surprise to anyone, the United States Preventive Services Task Force (USPSTF) published a very controversial recommendation in the Annals of Internal Medicine yesterday. The recommendation comes out strongly AGAINST the use of PSA in screening asymptomatic populations of men for prostate cancer. This follows from, and is consistent with, a draft recommendation from the same Task Force last fall.

Prostate Specific Antigen, or PSA, is an enzyme that is produced by the prostate. Measuring the amount of this protein in a blood sample has become the basis of a very popular and widespread screening test, since higher than “normal” amounts of this protein have been associated with prostate cancer.

Unfortunately the test is far from perfect, but proponents have argued strongly and persuasively that it is the best we have right now, and until research and medical science gives us a better test, men are better off being tested than not.

And so, asymptomatic men over a certain age, usually 50, have been encouraged by urologists, many oncologists and family physicians and most vigorously by prostate cancer survivors, patients and advocacy groups to have an annual PSA test, reasoning that if one’s PSA score goes up beyond normal, that is cause for further investigation, biopsy, analysis and so on.

Not so fast says the Task Force. It believes, based on actual evidence, that asymptomatic men who are tested annually for PSA levels fare no better than men who do not have the test at all. And if the test adds no predictive value, and does not prolong life, yet can do harm in the bargain, why should we be encouraging every man to have it?

And so the debate has raged for a decade or more. Since everyone already knew to expect a further heated debate when the Task Force recommendations were finally published, the Annals of Internal Medicine included two additional companion papers, one outlining the case supporting the guidelines authored by Dr. Otis Brawley of the American Cancer Society, and another arguing the case against the guidelines from Dr. William Catalona and a host of other colleagues, representing in the main the urology community .

So, who is this Task Force? The Task Force itself is a sponsored by the US government and its mandate is to review evidence and develop recommendations for preventive clinical services. The Task Force has come under significant pressure and criticism for its make-up – the Chair is a female pediatrician and apparently there may not even be any urologists on the panel, a feature that has literally infuriated the urological community and most prostate cancer patients and advocates.

So why, at the least, should the views of such a Task Force hold any credibility, and at the worst, shape public policy regarding prostate cancer screening?

Because they do have the credentials to their job, and their job is to review EVIDENCE and report back and recommend on the basis of facts, not fancy, to evaluate evidence, not conjecture and to analyze data, not articles of bias and faith.

And the facts and the evidence and the data have been increasingly clear over the last decade or more that the harms of PSA screening probably outweigh the benefits, and that is the spade that the Task Force has officially “called”.

How can this be true? How can the oft-taught and well-repeated mantra of early detection not always be right? The earlier you catch cancer, the better are your chances of treating and the better are a patient’s chances of surviving the diagnosis, right? To suggest otherwise surely goes against all logic, and certainly against all emotion.

Unfortunately for some cancers, the reality does not bear this out. Prostate cancer appears to be one of those cases where we have to look behind the apparent logic and see what the data actually tells us.

Now there is no doubt whatsoever that the PSA test does detect prostate cancers. That is unequivocally an undeniably true. However, not all men with prostate cancer have elevated levels of PSA – so the test is also prone to what we call false negatives.

More importantly, however, is that the PSA test also gives a lot of false positives – they alarm the patient to a possible prostate cancer that is not really there. In fact, PSA levels can rise for several reasons that are NOT prostate cancer – enlargement of the prostate (a very common malady among older men), inflammation or infection of the prostate and so on. Benign conditions that are NOT cancers yet the PSA test is not able to discriminate them very well.

So what is the harm of some false positives? Better to be safe than sorry, right?

Not if the false positive leads to an action that is more harmful than the disease it is trying to detect and prevent. Prostate biopsies are not pleasant, and can have lasting side effects. Treatments for prostate cancer can lead to many serious consequences – not the least of which is impotence, or incontinence, and other conditions that can severely and negatively affect a man’s quality of life.

Yet we know that the majority of prostate cancers develop late in life, are very slow growing and will never otherwise impair the health of the man harboring the cancer. The truth is that the vast majority of men will develop prostate cancer in their lifetime without them ever knowing it, and will die WITH prostate cancer (but NOT because of prostate cancer). Detecting a prostate cancer in these men may seem like a prudent course of action, but if they don’t know it’s there, and there is no ill effect ever from it, then what is the value of detecting it in the first place, especially if that leads one to consider or adopt a course of action that creates more harm and problems than it solves?

That is really the essence of the Task Force’s recommendation. The data simply do not show a clear enough benefit overall, and yet the risks of real harm are real and plentiful.

At this point, no one is saying that men cannot still get a PSA test if they and their doctor still feel it is warranted. And indeed for men at higher than normal risk, there may still be added value given their history or genetics.

Most organizations like the Canadian Cancer Society and the American Cancer Society indeed have positions that say that the right course of action for PSA testing is not in any way “outlaw” it, but in effect to use it more wisely, i.e., that the doctor and patient need to enter into a fulsome dialogue so that the patient is fully informed of the benefits and risks, and that some shared decision-making ensue as to whether PSA testing is right for him as an individual.

questionBut if we are to educate men at all, this dialogue MUST happen long before a blood sample is ever drawn. In my view, once there is a positive PSA test on the table, all bets are off – in effect the genie is already out of the bottle and it won’t easily get put back in.

Why is it too late at that time to discuss the pros and cons of investigation and/or treatment as opposed to just leaving the cancer alone?

Two simple words – “cancer” and “fear”. Despite the great strides we have made in treating and curing cancers, the very word “cancer” still conjures up in most people a fear like no other. The very thought, for most people, of knowing you have a cancer growing inside you does not allow you to ignore it on the grounds that it will do you no harm.

If a cardiologist tells you that have a mild heart murmur, you most likely will not quake in fear or demand a heart valve repair surgery. You will just learn to live with it and most likely will even ignore it totally as long as it remains asymptomatic.

But if an oncologist tells you that you have a cancer, your first thought is just as likely to be “Oh my God, I’m going to die” and the second thought that likely follows close on is apt to be “How do we get rid of it?” Ignoring it because it won’t do you harm is just not in most people’s psyche, even if it all evidence says that is what you ought to do…

And so, there is a school of thought that would say, if you can’t put the genie back in the bottle after a PSA test comes back positive, then don’t flirt with the genie in the first place.

Personally, I think this is a losing battle. I’m sure that every single prostate cancer survivor who had a PSA test is convinced that he is alive today because of that test. And in some cases, that is no doubt true. He is not concerned with statistics – he is a “sample of 1” – for him it is not a percentage bet, it is an all or nothing bet. And for every physician who will try to counsel him that getting the PSA test is just not worth the risks once the test result is in, there are countless others who will undeterred by sound and true epidemiological arguments but will revert to the argument of the “sample of 1”.

I think PSA testing is here to stay until we find a better test to oust it from the pantheon of questionable practices. All the sound, evidence-based and data-driven arguments of expert Task Forces who do know what they are talking about will not stem the tide in an era of over-testing, and over-diagnosis. We still have too much fear of the “C” word.

And the men who are harmed by all these good intentions may perhaps become bigger victims than those with cancers that are, and indeed ought to be, just left alone.

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Screening for Prostate Cancer- PSA Testing or Not?? — 1 Comment

  1. Excellent essay Michael. The bottom lines that when you have to be more worried about false positives than false negatives, the test is simply not discriminatory enough. There is a lot of work going on to develop more informative tests*. The message needs to be, testing is good but only if the benefits clearly outweigh the risks. Otherwise, we, the public, cannot be trusted to make the right decisions.

    * It’s also true that time series of PSA tests are somewhat more useful – if and only if, a significant increase is not acted upon immediately. in other words, there is heightened awareness not panic. In many renal cancers, this is the agreed upon approach – to watch and wait. Since even a kidney biopsy has significant morbidity interns of renal function, and because many benign lesions are detected through routine scans for other disorders, the result of an abnormal scan is not to intervene but to track. Only if the lesion significantly changes over time, is intervention warranted. Why is it that the prostate is treated so differently? It must relate to miscommunication of the outcomes of intervention vs nothing.