MOLECULAR FORMS OF PROSTATE-SPECIFIC ANTIGEN AND THEIR DIAGNOSTIC UTILITY IN PROSTATE CANCER

Abstract

Prostate cancer is the most commonly diagnosed malignancy in men. It is now the second cause of cancer death, exceeded only by lung cancer. The aetiology of prostate cancer is not particularly well defined. Possible risk factors include family history, age and race. The digital rectal examination (DRE) and serum prostate-specific antigen (PSA) level are the primary diagnostic tools. TRUS guided biopsy is further done for confirmation and histopathologic grading and staging.

Basic science and clinical investigations continue to look for new ways to enhance the clinical utility of the PSA test. In fact, several recent studies have shown that 70-80% of all biopsies are performed on men who do not have cancer. Because PSA is not cancer-specific, and prostate cancer develops in men at an age when other benign conditions are more prevalent, several methods to improve the sensitivity and specificity of the PSA test are being studied. These include the use of PSA density, PSA velocity, and the application of age­ adjusted reference ranges. Despite promising evidence in the clinical literature, none of these approaches has gained widespread acceptance.

Another option to improve PSA specificity stems from the observation that PSA exists in serum in several molecular forms including free, uncomplexed PSA and PSA complexed to several protease inhibitors, including alpha-1-antichymotrypsin