An early assessment of a new marker for prostate cancer, ‘Early Prostate Cancer Antigen 2’ (EPCA-2), was published in the April issue of the journal Urology by Dr Robert Getzenberg and his colleagues from the Brady Urological Institute and the Department of Pathology, Johns Hopkins University School of Medicine in Baltimore. The group had previously identified EPCA-2 as a protein associated with the cell nucleus in prostate cancer and in this study they used an antibody against part of the protein to measure it in blood samples using an enzyme-linked immunoadsorbent assay (ELISA).

The study tested several groups: men with prostate cancer either confined to or having spread from the gland, men with enlarged prostates (BPH), normal men and women, and men and women with a variety of cancers and other conditions. They chose a “cut-off” concentration for this marker as the highest value amongst those with no prostate disease. This then assigned raised values in 90% of those with cancer confined to the prostate and in 98% of those in whom the disease had spread, and  values were significantly higher in the latter group. These statistics were better than those for PSA. However, while only 23% of men with BPH had a raised EPCA-2, this was in a group specifically selected to have low normal PSA concentrations (<2.5 ng/mL).

If it is confirmed that the highest EPCA-2 values are found only when cancer has spread outside the prostate, such men may be able to avoid prostate surgery and go straight to X-ray and hormone treatment.   

The authors briefly reported a modification to the original assay. Normal men and women, and men after prostatectomy for cancer, all had similar very low values, and were clearly separated from the higher values in men with prostate cancer. No information was given about values in men with BPH or prostatitis using the modified method.

Further clinical trials are being undertaken to explore the potential of EPCA-2 as a specific marker for prostate cancer. Perhaps this work will herald a reduction in the number of undetected prostate tumours and unnecessary prostate operations.