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| Cancer screening |
Prostate cancer screening | |
Prostate cancer is the second cause of death by cancer in men (after lung cancer) and it is the most frequent cancer. It is characterised by a local phase during which radical treatment may cure it (however this treatment can be aggressive), and a metastasis phase for which only palliative measures are feasible, without modifying the poor prognosis, even if they can slightly increase survival.
Since the introduction of the PSA test (around 1990), many men between 50 and 70 have been tested. In the United States, due to the very important statistical work of the Registries (SEER study from NCI), it is clear that prostate cancer is now diagnosed at an earlier age, with a more limited stage than in previous years, but we still do not have scientific data proving that survival in prostate cancer patients has been increased.
PSA can be elevated by prostate cancer but also by other prostate diseases (benign hyperplasia, prostatitis, recent cystoscopy). Classically, one gram of cancer gives a blood level of 3 ng/ml whereas one gram of normal prostate 0.3 ng/ml.
Certain questions need to be clarified before systematically proposing a PSA test to men over 50.
Are all cancers detected after a PSA test clinically important? We know that, at autopsy, many old men have prostate cancer which has never be clinically significant (unfortunately we do not know their pre-mortem PSA value!).
Should we apply a variation according to age? It has been suggested to consider, as an upper PSA limit: 2.5 ng/ml up to 50 years, 3.5 ng/ml up to 60 years, 4.5 ng/ml up to 70 years, and up to 6.5 ng/ml after 70 years.
Should we use the free PSA / total PSA fraction as a way to better differentiate patients requiring biopsy when the total PSA is not very high?
Should we use the increase in the PSA value (the so called velocity) in order to avoid the great personal variability of PSA values?
There is generally a long period between the elevation of PSA and the clinical evidence of prostate cancer (at least 5 years). Smith and Catalona demonstrated that the pathological studies in patients who underwent radical prostatectomy because of prostate cancer detected by an elevated PSA revealed that 97% of cases were genuinely evolving cancers.
In fact, the real problem is knowing what to do with a localised prostate
carcinoma. Many treatments are aggressive and past controversies between surgeons
and radiotherapists have not improved the quality of the debate. What
should be proposed if the biopsy is positive?
- radical prostatectomy with many different procedures (open surgery, endoscopy) with a risk of impotence and urinary incontinence which is most often under-evaluated by surgeons,
- radiotherapy with many different procedures (external conformational radiotherapy, brachytherapy, associations) with a risk of impotence and rectal complications, also most often under-evaluated by radiotherapists,
- high-frequency treatments (whose risk is poorly known),
- systematic hormone therapy alone or in association with other treatments,
- watchful waiting - although this attitude has recently been criticised, it could be a possibility for older patients.
Randomised studies comparing the mortality of screened and non screened male populations are rare (study by Labrie) and although they have been criticised for their methodology, they tend to show that active treatment is necessary. The same conclusion is made in Scandinavian watchful studies and in their long term results.
Age at diagnosis should be treated with caution. Spontaneous survival according to age is well known. Low histological grade and associated pathologies may indicate watchful waiting or hormone therapy. However, men who enjoy good health at 75 may live long enough to run the risk of developing metastases and die in pitiful conditions inciting a more aggressive approach to their cancer.
Nowadays, in total honesty towards our patients and ourselves, we should recognise that we do not have sufficient knowledge to systematically propose prostate cancer screening. However the American Cancer Society, like the French Urology Association, recommends that all healthy men above 50 have an annual rectal examination and a PSA test. Men with a familial history of prostate cancer should be screened before the age of 50.
Our citizens want to be better informed. Before proposing the PSA test, it is necessary to clearly inform them of the consequences of a positive test.
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