To test for PSA or not to test
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Two recent studies published in the New England Journal of Medicine on March 26, 2009 look at Prostate Cancer screening and the mortality associated with the disease. The USA study known as PLCO randomized 76693 men half of which were in the screening group and half in the control group. Now most but not all those in the screening group had PSA tests and digital rectal exams while 40-50% of the control group had some tests. After 7-10 years the screening group had 50 deaths from prostate cancer while the control had 44 with no significant statistical difference between the two groups. The European study involved a larger number of 182000 men from seven different countries. Unfortunately each country had their own cutoffs for PSA being abnormal however mostly a PSA over 3 was abnormal whereas in the PLCO trial a PSA over 4 was abnormal. Overall there was a modest improvement in prostate cancer mortality with 261 prostate deaths in the screening group and 363 in the control. The difference barely met statistical significance. To prevent 1 cancer death over 1000 men would have to be screened and 48 other men would have to be treated. Unfortunately up to 50% of the prostate cancers detected by screening would never manifest any clinical symptoms during their lifetime. Many harms can be done once the cascade of biopsy and treatment begins. Side effects ranging from severe infections to loss of sexual function and urinary incontinence. So naturally the question arises what does one do in the light of these results? Clearly the science needs a way to distinguish who will have an aggressive disease versus a benign process and this information should be coming in the not to distant future. Until then we have to realize that many people with the diagnosis especially the elderly will not die of their cancer and in some instances watchful waiting may be the best option with screening to see if the disease is spreading before therapy begins. The patient needs to be informed of this diagnostic and treatment conundrum and if he is to go along with testing he should be given guidance along each step as to risks and benefits of watchful waiting versus aggressive therapy. The total patient should be considered including his age his family history other associated illnesses or disabilities which might be made worse by further testing or treatment and consideration should also be given to his work plus family situations. The first adage of medicine is do no harm and sometimes in our quest to slay anything that has the C word we may be leaving behind this basic tenet.
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