PSA (again)

     Every time I think that the question of PSA testing has been laid to rest, another outcry arises, sometimes pro and sometimes con. I realize that what we are dealing with here is a medical belief system, and belief systems are notoriously impervious to data and facts. I can recall the brouhaha that arose when one group announced that a clinical study showed no benefit of mammograms to women in the 40 to 49 year old age group.

     Let us begin again by realizing that no one argues about the speed of light, or whether or not Albany is the capital of New York State, or if 7 x 8 = 56. No one usually argues about agreed-upon facts that can be measured. The problem arises when two people  try to fit the same data into two different  heuristic structures, because your theoretical picture will frame and interpret the data you view, as all epistemologists acknowledge. There is even more argument when we try to interpret or predict  the result of an intervention on human behavior: we still cannot agree on whether or not the data shows that teaching about sex education and contraception  in high school encourages high school students to have sex. As a general rule, when the data does not lead to an immediately verifiable conclusion (viz. the question of global warming) there is a tremendous amount of heat generated in the argument/discussion with correspondingly little light.

     The broadest discussion to date about the pros and cons of screening with the PSA is contained in this month's issue of the Annals of Internal Medicine (17 July, 2012) , vol. 157, no. 2. There are three articles: The USPSTF (U.S. Preventive Services Task Force) recommendation against PSA screening, with the proviso that the final decision should be one  of "shared decision making" between the doctor and the patient (pp 120-134), a shorter review which concurs with the recommendation of the USPSTF (pp 135-136), and an equally short review that opposes the recommendations (pp 137-138). I will  summarize the three articles from a strictly scientific point of view ---i.e. based on the data cited,  and then try to illustrate where personal beliefs and projected feelings about the quality of life with and without  treatment  may have crept into the discussion. I will also carefully point out the unknowns in this decision making. And let us not forget that the USPSTF recommendations are only recommendations, and each patient will make a decision that is ego-syntonic with his own medical belief system.

     First a caveat. In my practice I have never seen a wife permit her husband to do "watchful waiting" once a biopsy shows prostate cancer. So if you are a husband who would not agree to any treatment, then don't ever do the PSA test.

     1) The only screening method referred to in all the studies is the serum PSA, and not a rectal exam.

     2) More men die with prostate cancer that from prostate cancer. In the latest autopsy study, 70% of men in their 70's have microscopic foci of prostate cancer.

     3) Some groups are at increased risk for prostate cancer: black men and men with first degree relatives who have or have had prostate cancer.

     4) If we define "overdiagnosis" as the detection by PSA of a tumor that will not spread and cause symptoms in the patient's lifetime, then the two largest trials suggest overdiagnosis rates of 17% to 50%.

     5) No study reported on the effect of screening on the development of metastatic disease.

     6) In looking at all the studies, the chance of a non-screened man of dying from prostate cancer in 10 years is 5 in 1,000. The chance of a screened man dying is either 4 or 5 in 1,000, so the net benefit is between 0 and 1 man per 1,000 men screened.

     7) NO study showed a reduction in all cause mortality(!) The one study that showed a slight decrease in mortality from prostate cancer showed an increase in deaths from other causes, usually cardiovascular, so there was no net extension of lifespan that resulted from PSA screening.

     8) When the PSA cutoff is between 2.5 and 4.0, the false positive PSA rate is 80%.

     9) Overdiagnosis makes screening appear to save lives when it does not do so.

     10) The median follow-up time was 10 years.

     11) Because of lead-time bias, patients diagnosed earlier by asymptomatic screening appear to live longer with cancer. This is a problem with all screening methodologies for all fatal diseases.

     12) The American Cancer Society and the American Urological Society both recommend informed decision making rather than routine PSA screening.

     13) Radiotherapy and surgery both cause urinary incontinence in 20% of those so treated and erectile dysfunction in 30% (on the average).

     14) Radiotherapy can also cause chronic diarrhea and/or colonic irritability.

     15) "We need to practice medicine on the basis of evidence and not on the basis of faith."

     And again, despite all recommendations and readings, there is no substitute for a full discussion with your family doctor of your likes, your dislikes, your wishes, your fears, and your desires. You should never feel pressured into making a decision about your health with which you do not feel comfortable. It is your body and your mind, and you have to live comfortably with them both. And once you make a decision, please don't second-guess yourself. (You  have enough well-meaning friends who will do that for you.)

   

To PSA or Not To PSA, That is the Question

     In view of the recent hooraw over whether or not testing for and treating prostate cancer saves lives, I feel I should re-visit this subject, which I first discussed in my blog of May 15, 2009. I want to begin by emphasizing once again, speaking as a trained scientist, that in any given field what counts is what we can show to be true by experiment, and not what we can deduce or think  should be true (with Einstein's Theory of General Relativity being a notable exception, but even that theory was based upon an experimental result, namely the equivalence of inertial and gravitational mess, as first shown by Galileo). It also doesn't matter what we would like to be true, because Mother Nature's rules are independent of our beliefs.

     Some of the examples of medical facts and treatments that we thought should be true or benefit patients but were shown to be false or harmful or not proven when subjected to clinical testing are:

1) If a patient has calcium oxalate kidney stones then the proper treatment is toDEcrease the amount of calcium in the diet.

2) Beta-blockers should never be used in a patient who is in heart failure.

3) Everyone needs 8 glasses of water or fluid a day for good health.

4) Everyone needs at least one bowel movement a day.

5) If a patient is ill, bleeding with leeches will generally make him/her better.

6) An hour of sleep before midnight is worth two hours after.

7) If you go swimming right after eating you will develop an abdominal cramp and drown.

8) Vitamin E, because of its anti-oxidant properties, prevents heart attacks.

9) Beta-carotene, because of its anti-oxidant properties, protects smokers from lung cancer.

10) Mammograms taken between the ages of 40 and 50 saves lives.

11) The optimum time interval between complete physical exams is one year.

12) The optimum time interval between colonoscopies is 10 years.

13) The optimum time interval between mammograms is one year.

14) A drink of alcohol a day cannot possibly be good for you.

15) Daily doses of saw palmetto help treat an enlarged prostsate.

16) Daily doses of gingko balboa help prevent Alzheimer's Disease.

     I could easily add another 10 to 20 pseudofacts to the above list. Now let us look at the question of PSA testing as well as the treatment of prostate cancer. Before asking whether or not measuring the PSA saves lives, we first have to determine if treating prostate cancer saves lives. As of today, there is absolutely no evidence that it does. It may seem counterintuitive that this is so, but the fact is that the majority of men die WITH prostate cancer, and not OF prostate cancer. Roughly speaking, the percentage of men who have prostate cancer at autopsy is equal to their age at death: 70% of men at age 70 have microfoci of prostate cancer, etc. Much as we would like to believe that detecting prostate cancer early and treating it will save lives, there is absolutely no evidence that this is so.

     There have been many review articles coming to this conclusion, and you can check PubMed, the abstract archive of the National Institutes of Health for references. So why do people do the PSA, or take treatment if a prostate biopsy shows prostate cancer? The answers are many and varied, and all are ultimately the result of individual decisions by individual patients. Some of the reasons are:

1) Some people cannot tolerate the thought of having cancer within their bodies.

2) Some wives cannot tolerate the thought that their husband is walking around with cancer.

3) Some men believe that treatment of prostate cancer will save their lives.

     Very few men are told that most prostate cancers detected on biopsy will not spread and kill them. Very few men are told of the possible lingering (6 months to 2 years) or permanent symptoms of radiation proctitis that can result (chronic bloody or non-bloody diarrhea). Many men don't fully understand the implications of the fact that 30% of treated men will develop urinary incontinence (and need to wear a diaper) or be unable to mount or maintain and erection (even with the help of Viagra), or both.

     Since a physician's first duty to his/her patient is to "do no harm", I lay out all the above info to my patients, and if asked, I tell them that I never have taken a PSA test and would never treat prostate cancer in myself. However, if a patient decides on treatment, I urge him to consult with both a urologic surgeon and a radiation oncologist to listen to the pros and cons of each procedure, and then to consult with a medical oncologist for an overall view. I also suggest that he not discuss his decision with any friends who have been treated in order to avoid impassioned but not dispassionate arguments and lectures. And then I remind him that it is his body, that he is the patient and must make the final decision, and not to do any treatment or non-treatment that he does not fully agree with.