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Blood Test to Predict Organ Confined Prostate Cancer Before Undertaking Surgery
April 7, 2000 /PSA Rising/. One of the drawbacks of radical surgery for prostate cancer is the difficulty of predicting ahead of time whether the cancer will prove to be localized, that is confined to the prostate gland and not escaped beyond the "capsule" containing it.
In the effort not to subject a man to pointless surgery, conscientious urologists consult PSA, "free" PSA, Gleason score based on biopsy and results of scans. Even so, a percentage of men who undergo surgery are found to have disease beyond the prostate itself.
Urologists in Hamburg, Germany and Malmo, Sweden have developed a new test, human glandular kallikrein 2 (hK2), for improving prediction of organ-confined disease. In the Journal of Urology May 2000 they report that they measured serum levels of human glandular kallikrein 2 (hK2) in patients with prostate cancer who were about to be treated with radical retropubic prostatectomy.
They wanted to see whether measuring hK2 levels ahead of surgery can distinguish stage T2a/b prostate cancer from T3a or greater cancer. "This finding," they say, " would help to predict preoperatively the organ confined versus nonorgan confined growth of prostate cancer."
They tested on a series of 68 men who underwent radical retropubic prostatectomy for clinically localized prostate cancer. Serum was drawn 1 day before the surgery, before the prostate was handled. hK2, and total and free prostate specific antigen (PSA) were measured. Mean, median and range of hK2, total and free PSA, and the ratio of free-to-total PSA (percent free PSA) were calculated. Each factor or combination of factors was evaluated to determine whether it significantly contributed to enhance the discrimination of organ confined from nonorgan confined cancer.
As it happened, after all the surgeries were performed and the tests assessed, it was found that 38 of the men had organ-confined disease and 30 had nonorgan (extraprostatic extension). The group of 30 less fortunate men represent those who might stand to benefit from future development of this and similar tests. Had they known the results ahead of time, they might have chosen not to go ahead with surgery.
In organ confined cancer, the researchers found, " mean hK2 was significantly lower than in nonorgan confined cancer (0.09 ng./ml., range less than 0.03 to 0.23 versus 0.30, range 0.04 to 0.94, p
HK2 was a more sensitive test. More than a third of the time (37%) it was a 100% accurate, giving correct identification of all nonorgan confined cancer. This compared with a sensitivity of 14% for total PSA.
At a specificity of 95%, sensitivity was 40% for hK2 versus 23% for total PSA, a statistically significant gain in sensitivity (p
Compared with total and free PSA, the researchers say, "hK2 testing improved the preoperative evaluation of patients who underwent radical retropubic prostatectomy due to the superior discrimination of organ from nonorgan confined cancer."
J Urol 2000 May;163(5):1491-1497 Human Glandular Kallikrein 2: A Potential Serum Marker for Predicting the Organ Confined Versus NonOrgan Confined Growth of Prostate Cancer. Haese A, Becker C, Noldus J, Graefen M, Huland E, Huland H, Lilja H Department of Urology, University Clinic Eppendorf, Hamburg, Germany, and Department of Clinical Chemistry, Lund University, Malmo, Sweden.
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