Gezielter Einsatz des Tumormarkers PSA

Abstract

Tumor markers are being used in the early detection of cancer disease, diagnostics, prognosis, therapy and disease follow-up. A lot of clinical studies would not be nowadays possible without tumor markers. As in clinical practice the informative value of results is limited (by limited sensitivity and/or specificity) those markers should be selectively used, i.e. in such clinical setting where there is a clear benefit. Prostate specific antigen (PSA) has become the most important tumor marker in oncology. Its importance ranges from early detection of prostate cancer until therapy decision making in hormone refractory cancer. To prevent initial PSA- "terrorism" in early detection the patient must be well informed about risk of prostate cancer and therapeutic options inclusively possible side effects. Does the man at risk agree further evaluation by biopsy has to be performed directly above a PSA-cut-off 4.0 ng/ml. A high percentage of free PSA is not allowed to prolong diagnostic procedure. On the opposite, in PSA range 3.0-3.9 ng/ml and free-to-total PSA ratio less than 12% a prostate biopsy is also indicated. The diagnostic "grey zone" 4.0-10 ng/ml does not exist any more. Further follow-up should be done if the estimated life expectancy exceeds 10 years and should be performed in the PSA-range 2.0-3.9 ng/ml annually, in the PSA-range 1.0-1.9 ng/ml biannually and in the PSA range less that 1.0ng/ml triennially. About 3-25% of newly detected cancers are clinically insignificant. Models based on PSA, Gleason Score and tumor load of biopsies are helpful in identifying these men for "active surveillance" in curative intent. "Not every early detected cancer must be cured, but cancer where cure is necessary, must be early detected!" After primary therapy (operation/radiotherapy) one third of men will document a PSA only relapse. 30% of them will develop clinical symptoms and possible die from disease. PSA and especially PSA doubling time is a promising marker to identify these men at risk for whom salvage-radiotherapy, salvage prostatectomy or hormonal therapy can be an option. However the benefit in survival must be weight against a possible loss in quality of life.