UroToday- The steady decrease in prostate cancer mortality is indirect evidence that prostate cancer early detection using serum PSA and the digital rectal examination saves lives. Nevertheless, the use of serum PSA for prostate cancer screening remains controversial due to its low specificity. Developing additional serum tumor markers for early detection would prove invaluable for improving early detection while reducing the number of unnecessary biopsies.

In the April issue of Urology, Leman and colleagues describe the performance characteristics of EPCA-2, a novel nuclear protein marker for prostate cancer cells. EPCA and EPCA-2 were identified at Johns Hopkins using proteomic technology to analyze the subcellular protein composition of prostate cancer cell nuclei.

Banked serum from several subsets of patients was used including: 63 men with a serum PSA less than 2.5 ng/ml and a normal DRE (30 of those had undergone a negative 12-core biopsy), 80 men with prostate cancer (40 organ-confined and 40 non-organ confined), 35 men with symptomatic BPH, and men with prostate cancer and PSA levels less than 2.5 ng/ml and (5) 134 controls.

In men without cancer, the EPCA-2.22 ELISA assay had 92% specificity (95% CI, 85% to 96%) and 94% sensitivity (95% CI, 93% to 99%) for prostate cancer using a threshold value of 30 ng/mL. In men with a diagnosis of prostate cancer, EPCA was found to have a sensitivity of 90% and 98% in men with organ confined and non-organ confined disease, respectively. Interestingly, the EPCA-2.22 serum assay was effective in differentiating patients with localized disease versus extraprostatic extension with an area under the curve of 0.89 (p < 0.0001).

This exciting study suggests that the EPCA-2 protein serum assay exhibits favorable performance characteristics which are potentially superior to serum PSA. Whether this test will retain its sensitivity and specificity when used in a screening population remains to be studied.

Leman ES, Cannon GW, Trock BJ, Sokoll LJ, Chan DW, Mangold L, Partin AW, Getzenberg RH

Urology. 69(4):714-20, April 2007
doi:10.1016/j.urology.2007.01.097

Reported by UroToday Contributing Editor Ricardo F. S??nchez-Ortiz, MD

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