Since the early 1990s, screening for prostate cancer is based on digital rectal examination and a blood assay, called PSA. But U.S. researchers show that good results do not eliminate the risk of tumor. The annual evolution of the SAP would prove a much better indicator.
Screening for prostate cancer depends on the dosage in the blood of a specific marker of a dysfunction of the prostate (called PSA specific antigen). But for several years, this review is in jeopardy …
A low dosage does not increase the risk of cancer
ProstateQuelle cancer is the actual reliability of the PSA assay? To provide a definitive answer, the team of Ian Thompson has enrolled nearly 10 000 men over 55 years1. For seven years on average, each of them has suffered an annual PSA assay, digital rectal examination and biopsy. Of normal rectal touch (no perception of abnormal area on the gland) and dosages PSA below 4 ng / ml are usually associated with a low risk of cancer. Among men participating in the study, 2 950 fell into this category.
But after a biopsy, no less than 449 (15.2%) of them turn out to be cancer patients, 67 of which were sophisticated.
A low dosage of PSA therefore does not eliminate the risk of prostate cancer. Can we lower the threshold of danger? No, according to the authors, since even very low PSA assays may actually hide cancers: it was for 6% of dosages below 0.5 ng / ml.
Therefore impossible to eliminate the risk of tumor regardless of the PSA assay! Should we thus lay forgotten this indicator to the poor predictive value? No, judging by another U.S. study that offers an original use.
The evolution of PSA is a better index
Inventor of the PSA test, Professor William Catalona2 could once again disrupt the screening of prostate cancer. His team followed 1 095 men with localized cancer of the prostate gland (early stage of the disease), practicing every 6 to 12 months of PSA assays, the touches and rectal biopsies. Between 1989 and 2002, all were treated with radical prostatectomy (removal of the prostate gland). During the five years following the operation, 366 recurrences and 84 deaths occurred, including 27 due to cancer.
By analyzing PSA assays collected one year before diagnosis, the researchers were interested in the rate of rise and its influence on the future of the patient. To their surprise, an increase of more than 2 ng / ml during this period was found associated with risk of death from prostate cancer almost 10 times higher!
The authors estimate that a single dose of the PSA is less important than its trend during the year preceding diagnosis. For this development, and each dosage early years are necessary.
Tomorrow, a change in clinical practice
Currently, a biopsy, the digital rectal examination and PSA assay to estimate the danger of cancer and to choose from simple monitoring to more radical treatment including removal of the prostate (radical prostatectomy) and radiotherapy systematic . But do not take into account changes in the PSA assay seems no longer possible as confirmed by Professor Catalona “Our results suggest that men whose PSA is rising fast should not be a simple Surveillance (…) and many of them require a more aggressive than the radical prostatectomy to prevent death from cancer of the prostate.
“The evolution of assays of PSA was a factor that we take into account already. Nevertheless, this study has the merit of giving a value of changes in PSA level above which a more radical is needed” we said Dr. Lawrence Alexander, surgeon-urologist at the hospital Kremlin-Bicêtre.
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