WBA. Zin en onzin PSA bepaling en prostaatbehandeling L. Denis Oncologisch Centrum Antwerpen 25 april 2005. PSA: a serine protease enzyme secreted by epithelial cells of the prostate. In the serum as a free uncomplexed form ACT alpha-1-antichymotrypsin
Zin en onzin PSA bepaling en prostaatbehandeling
Oncologisch Centrum Antwerpen
25 april 2005
In the serum as a free uncomplexed form
alpha 2M alpha-2-macroglobulin
other acute phase proteins
Identified in 1982 as follow-up marker.
in 1987 as diagnostic marker.
in essence tissue marker
A marker produced by cancer cells, detectable in body fluids, easily measurable.
A PCa marker, PSA is tissue specific becomes a tumour marker after diagnosis.
Long evolution of disease in elderly patients (co-morbidity) make prognostic value (surrogate marker of survival) difficult.
L. Boccon-Gibod, 2005
Total PSA equimolar response for free and PSA ACT complexes.
Free PSA in serum separated in 3 hours and assayed in 24 hours.
Reference values to be established for each assay combination.
1. April results Helsinki not taken into account (extreme outliers)
Prior to any treatment (repeat once).
After treatment with curative intent.
After treatment hormones/medication.
With a cut-off point of 4 ng/ml, 20-30% of cancers will be missed
Only 1 in 4 men with a PSA level of 4-10 ng/ml will have PCa following needle biopsy
The optimal upper limit of normal for PSA for PCa screening is unknown. New biomarkers are needed linked to prognosis and prognostic validated trials.
I. Thompson, 2004
DUST study shows that PSA, PSA D, TZ.PSA D and% free PSA do not enhance specificity for PCa detection in PSA 3-15 ng/ml.
Michielsen D. et al, 2005
The final pathology or predictive value by t PSA or symptomatic biopsy is not improved by % f/t PSA.
Miyake H., 2005
Using invalidated combinations of f and t assays may increase the number of unnecessary biopsies. Cut points need to be validated for each individual assay.
Oberpenning F. et al, 2002
Based on cysto-prostatectomy specimen it appears that the biologic activity appears to be independent of serum PSA.
Ward et al, 2004
Schröder: PPV of PSA 3,0 ng/ml is 20% and
correlation remains significant.
Catalona: Correlation PSA & % Ca (.37-47)
Cancer Volume (.43-48)
Prostate Volume (.01-17)
Serial measurements vs. tissue (BPH) specificity.
After surgery o and other treatment’s nadir is a rise therapy failure (Biochemical relapse).
Nadir with hormonal treatment predictive for response duration.
HRPC a 50% reduction and slope show response (other markers needed).
Discovered as a concept in 1970 and developed into the PSA test has never been specific enough to be a definitive test for Pca.
The PSA related concepts are flawed and lead to unnecessary treatments.
A more specific test is needed and PSA is more a smoke than a fire alarm.
Richard J. Ablin, 2001