Leaders Latest tests for prostatic neoplasia

Despite being the second most common cancer in males, and one from which mortality is increasing, cancer of the prostate remains in many ways an enigma. For example, little is known of its pathogenesis, although the androgenic hormones are clearly important, the incidence increases with age, and genetic factors also have a role. Furthermore, while its development appears to involve a progression from normal tissue through increasingly severe grades of dysplasia to intraepithelial neoplasia and thence to invasive cancer, there is considerable variation in the rates of progression to invasive disease. Indeed, previously unsuspected prostatic cancer is frequently found at necropsy and in men undergoing surgery for benign disease. The diagnosis of prostatic cancer is histopathological and generally made from biopsy material. The decision to perform a biopsy may sometimes be based on clinical evidence alone, but for any cancer a diagnostic test to indicate its presence before it is clinically apparent should be of value (depending on the availability of eVective treatment and the outcome if treatment is delayed). The screening tests available for prostatic cancer are digital rectal examination, transrectal ultrasound, and serum prostate specific antigen (PSA). Neither of the first two is suYciently reliable on its own. In practice, measurements of PSA are used to decide whether to perform ultrasound examination as a preliminary to possible biopsy. However, PSA measurements can be used in several ways. Unusually for a common tumour, there has long been a blood borne marker for prostatic cancer, namely prostatic acid phosphatase (PAP), first described in 1938. However, PAP was not suYciently sensitive or specific to be useful in screening, although it was of value in monitoring the response to treatment of patients with invasive disease. Prostate specific antigen (PSA) was identified in semen some 30 years later, and first isolated from prostatic tissue in 1979. The first report of its potential as a tumour marker for prostatic cancer appeared shortly after and within a short time PSA had become the preferred marker and PAP became regarded as obsolete. Indeed, PAP has by now been deleted from most laboratories’ repertoires. But how reliable is PSA as a test for prostatic cancer? Are multiple measurements more reliable than single measurements? Does the measurement of free PSA oVer any advantage over that of bound PSA? And will PSA eventually go the way of PAP—are there any other tests for prostatic cancer in the oYng? There are thousands of research papers on this topic and any review must necessarily be highly selective. Several more comprehensive reviews on screening for and managing prostatic cancer have been published recently.