Novel PSA test detects ‘undetectable’ antigen levels post-prostatectomy
By Sarah Guy
30 September 2010
Fourth AACR International Conference on Molecular Diagnostics in Cancer Therapeutic Development; Denver, Colorado, USA: 27–30 September 2010

MedWire News: US researchers have developed a novel method to detect serum prostate-specific antigen (PSA) levels in men who have undergone surgery for prostate cancer.

Standard PSA tests are often unable to detect the very low PSA levels expected after radical prostatectomy, explains the team, who have developed a test that measures individual PSA molecules rather than overall PSA levels in blood samples.

"After radical prostatectomy, many important questions remain for the physician and the patient," said David Wilson from the Quanterix Corporation in Boston, Massachusetts.

"AccuPSA is designed to help the physician and patients to become better informed by measuring PSA after radical prostatectomy and establishing if the cancer is gone or has metastasized or recurred," he added.

In preliminary validation studies, the AccuPSA test - which uses Single Molecule Array technology to separate individual PSA molecules and count them - showed a lower detection limit of 0.01 pg/ml, and a quantification limit of less than 0.05 pg/ml. The assay also demonstrated good agreement with a standard PSA test when used to detect higher PSA levels.

For the current study, the team analyzed blood samples from 60 post-prostatectomy patients whose PSA levels were too low to be detected using a commercially available test. The AccuPSA test gave measureable PSA levels for all the men, with the lowest measured at 0.014 pg/ml.

Wilson and team hope that their test will be used in the future to satisfactorily proclaim radical prostatectomy patients "cured" of prostate cancer when their PSA levels are truly undetectable.

Equally, the team hopes to establish that nadir values - the lowest value of PSA that occurs post-surgery - are predictive of prostate cancer recurrence.

"AccuPSA has the potential to eliminate unnecessary treatments and enable earlier detection of recurrence, which may lead to earlier treatment, better outcomes, and a positive impact on healthcare costs," concluded Wilson, who presented the data at the Fourth AACR International Conference on Molecular Diagnostics in Cancer Therapeutic Development in Denver, Colorado, this week.

MedWire ( is an independent clinical news service provided by Current Medicine Group, a trading division of Springer Healthcare Limited. © Springer Healthcare Ltd; 2010

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