New serum tests for the diagnosis of prostate cancer

Prostate-specific antigen (PSA) has had a profound impact on the early diagnosis, treatment and follow-up of prostate cancer, the most common malignancy in men. However, it is not only a marker for prostate cancer but is also often expressed in benign conditions such as benign prostatic hyperplasia, prostatitis and other inflammatory disorders. For early detection of prostate cancer, limitations of the use of PSA become obvious; its widespread use has led to extensive expensive and often unnecessary diagnostic procedures associated with significant morbidity. New serum tests derived from total PSA may play a key role in enhancing the accuracy of prostate cancer diagnosis. The ratio of free to total PSA improves specificity while maintaining a high sensitivity for prostate cancer detection for men with a total PSA of 2.5-10 ng/ml who also have a normal digital rectal examination. Human glandular kallikrein 2 also has the potential to be a valuable tool in combination with both total and free PSA for the early diagnosis of prostate cancer. However, the optimal clinical use of human glandular kallikrein 2 still remains to be clarified. Complex PSA seems to be a reliable tool and equivalent alternative to total PSA to improve specificity at high sensitivity levels in men with suspected prostate cancer, mainly for PSA levels below 4 ng/ml. Several newly discovered isoforms of free PSA (bPSA, [-2]pPSA and inactive intact PSA) may also impact the early detection of prostate cancer, with encouraging preliminary results that warrant further clinical investigation.