Complexed Prostate Specific Antigen (cPSA) assay has been shown to offer higher specificity than total PSA (tPSA) for the detection of prostate cancer
Men who attend the WellMan Clinic in London's Weymouth Street for regular health check-ups are now routinely tested using Bayer Diagnostics's unique Complexed Prostate Specific Antigen (cPSA) assay, which the company says which has been shown to offer higher specificity than total PSA (tPSA) for the detection of prostate cancer.
The WellMan Clinic became the first private clinic in the UK to use cPSA in 2004, utilising the rapid testing service offered by nearby HCA Laboratories which runs the assay on an Advia Centaur immunoassay system.
"The cPSA test is much more specific for identifying early prostate cancer than the old tPSA test which registers a high result for many benign conditions", says the clinic's medical director, Richard Petty.
"Use of cPSA reduces the number of instances where we have to send patients for further investigation.
"The reason being we now find that a greater proportion of cPSA results are normal than they used to be when were measuring tPSA.
"This saves many patients from having to undergo trans-rectal ultrasound and biopsy procedures unnecessarily".
The WellMan Clinic uses a cut-off point for cPSA of 3.6ng/ml in order to select patients for further investigation.
Blood samples are initially obtained from patients and transported to HCA Laboratories using an hourly courier service.
Results are reported within four hours, allowing men who attend a morning appointment to be given their results on the very same day.
Around 20-30 cPSA tests are requested by the clinic each week.
In cases where the result is 3.6ng/ml or above, the patient is immediately sent across to a specialist private diagnostic centre in neighbouring Harley Street where the anatomy of the prostate is examined in detail using Doppler colour ultrasound technology.
If abnormal tissue density is detected in conjunction with an increase in blood flow, a biopsy sample is immediately taken using the ultrasound as a guidance tool.
Biopsy samples are then sent for histopathological analysis, with results available within two days.
"We have compared results from the cPSA and tPSA tests, and found that the quantum of cPSA is usually around 40% lower", says Petty.
"You can expect a gradual rise in the PSA measurements as men get older and their prostates get bigger, but discovery of a sudden upturn - even within the normal range - always causes us to trigger an investigation.
"I think tPSA has now been rather discredited as a test, and we could never make much sense of free PSA (fPSA) because it is so labile and degrades very quickly.
"cPSA is so specific because it is produced by cells which can be defined as being cancerous, and we now have enough experience with the test to be extremely confident about the results.
"Those clinicians who have yet to be convinced about cPSA should try it for themselves."
