Prostate Cancer

Advantages of the DiaPat®-PC test

Test procedure

Validity/studies


Advantages of the DiaPat®-PC test  

Fig. 1: Advantages of the DiaPat®-PC-test

¹ Dan Theodorescu et al., 2008, PROTEOMICS Clinical Applications
² Brawer MK, 1999, CA Journal
³ Terris, 1999, Adult Urology; Shinghai u, Terris, 1999, Adult Urology 

 
The DiaPat®-test is a sensible follow-up test, subsequent to the determination of the PSA-value.

Especially in view of the problem posed by the relatively low specificity of the PSA-test, yielding around 70% false positive results, the DiaPat®-test has been directly compared to the significance of the PSA-value as well as the free PSA / total PSA ratio. And this it precisely where the advantages of the DiaPat® method become evident:

We focused our studies on the PSA-range of 2-20 ng/ml and while the sensitivity of the PSA-value , with > 90%, was very high, specificity, more precisely the correct exclusion of cancer, was only achieved in a small number of individual cases, yielding a specificity of < 10 %. The DiaPat-test in contrast is characterised by high sensitivity of around 90% in combination with high specificity of around 60%.

For this reason, the DiaPat®-test makes it possible to avoid unnecessary biopsies, while maintaining the sensitivity. 
Validity

Compared to invasive diagnostic methods the advantages of the DiaPat®-test are obvious:

The DiaPat®-test does not affect everyday life, because it does not require any pre-treatment or aftercare (e.g. taking antibiotics).

The collection of a urine sample presents a substantially less time-intensive method for the patient than a diagnosis requiring invasive methods.

In case of negative findings, the DiaPat®-test can be repeated anytime as control test. Positive findings give patient and consultant a clearer indication for a biopsy than, for instance, PSA results. In 70 % of all cases, PSA tests provide false positive results, i.e. pathological changes are indicated, when in fact no cancer is actually present.

Fig. 2: The „blind area" of the prostate biopsy

DiaPat® doesn’t want to substitute the biopsies completely, at least the unnecessary interventions (only in Germany approx. 500,000) and the high risks which go out from the biopsies, like inflammations, bleeding and and the life danger not to be excluded¹ help to avoid.

The possible metastasis of the cancer², as well as the change of a quiescent cancer (prevailing majority) in an aggressive cancer can be caused by the prostate gland biopsy.

¹ Wefer et al., 2000, The J o Urology
² Terris, 1999, Adult Urology

                        
Test Procedure 


Fig. 3: DiaPat®-test procedure

1) Call our service hotline on +49 511-5547440 contact us by e-mail, arztinfo@diapat.com
2) DiaPat®-test package is despatched
3) Patient signs the DiaPat® contract
4) Collection of urine sample (sample taking instructions and accessories are provided together with the DiaPat®-test)
5) Freezing of urine sample (3*-icebox is normally sufficient)
6) Call free collection service
7) Analysis of urine sample in the DiaPat laboratory
8) Test results are sent to your surgery


Validity/studies

The continuation of the pilot study with further 534 patients confirmed the high reliability. Here, sensitivity of 89% and specificity of 51% was achieved. The use of an alignment chart, which includes the age of the patient as well as the percentage of free PSA into the diagnosis, achieved 91% sensitivity and 69% specificity in the blinded patient cohort.
A total of 22 different study centres in Germany and the US, amongst them 2 universities and 20 GP practices, participated in this study.

Discovery and Validation of Urinary Biomarkers for Prostate Cancer
Dan Theodorescu, Eric Schiffer, Hartwig W. Bauer, Friedrich Douwes, Frank Eichhorn, Reinhard Polley, Thomas Schmidt, Wolfgang Schöfer, Petra Zürbig, David M. Good, Joshua J. Coon, Harald Mischak
PROTEOMICS – Clinical Applications 2007

Abstract  

In July 2007, a summary of studies focusing on prostate cancer has been published in  „Der Urologe“, the official journal of the association of German urologists (Berufsverband der Deutschen Urologen) and the German society of urology (Deutsche Gesellschaft für Urologie).

An initial pilot study [1] demonstrated that the proteomic analysis of urine allows the  differentiation between prostate carcinoma and benign changes of the prostate, these findings, however, are based on a small number of cases(n=47) for the time being.
In contrast to other examined indications, such as for instance urothelial carcinoma, it appears that in the case of prostate carcinoma prostate secretion, and not urine, is the body fluid carrying the information [2, 3]. On this basis, the working hypothesis was derived, that the first 10 ml of urine (initial stream urine) contain sufficient secretion to allow the diagnosis of prostate carcinoma. In addition, initial stream urine in contrast to post-prostate massage urine can be obtained without palpation of the prostate.
One of the difficulties occurring in the proteomic analysis of initial stream urine is that the proportion of prostate secretion in the urine varies and can not be determined directly. For this reason, an “informative polypeptide pattern“ has been established first of all to identify initial stream samples containing sufficient prostate secretion. In order to identify polypeptides which are specific for first stream urine, 116 initial stream urine samples have been compared with 320 midstream urine samples (which should only contain little secretion).

This “informative pattern“ was used as selection criterion to establish a protein pattern indicative of prostate carcinoma, and subsequently only samples featuring this pattern were used. 106 of the 116 initial stream samples of patients with prostate carcinoma, benign prostate biopsy results, chronic or acute prostatitis and subjects without prostate complications met this “informative criterion“.

In another step, these 106 samples were used to define biomarkers and a diagnostic pattern of prostate carcinoma. The pattern has been validated in a blinded study with further 81 subjects. In this context, the rate of correct classification achieved was 88.4% for carcinoma and 59% for the non-malignant samples.
It has to be noted, that the results of the prostate biopsy were used as “gold standard“ in the classification- i.e. while all carcinoma cases can be diagnostically regarded as well-founded, the same assumption can not be applied to negative biopsy results. For this reason, prostate carcinoma could be detected in 7 cases after a second biopsy was carried out in 9 patients with initial negative biopsy results, but who were classified as malignant in the proteomic analysis.

[1] Pilot study of capillary electrophoresis coupled to mass spectrometry as a tool to define potential prosta­te cancer biomarkers in urine
Dan Theodorescu, Danilo Fliser, Stefan Wittke et al.
Electrophoresis 2005 (26): 2797–2808

[2] Hu­man kallikrein 4: quantitative study in tissues and evidence for its secretion into biological fluids
CV. Obiezu, SJ Shan, A. Soosaipillai et al
Clinical Chemistry 2005 ( 51): 1432–1442

[3] Fast and novel purification method to obtain the prostate specific antigen (PSA) from human seminal plas­ma
B. Acevedo, Y. Perera, E. Torres et al.
Prostate 2006 (66): 1029–1036



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