Genetic signatures on prostate biopsy: clinical implications
Prostate cancer management remains a topic of intense debate given favorable disease-specific outcomes for the overwhelming majority of patients. Consensus regarding the role of prostate-specific antigen (PSA) screening among the general male population has been elusive, in part due to questions surrounding the reliability of prostate biopsy results and the difficulty identifying patients with localized disease who will one day progress. Until recently, the Gleason score has been the best prognostic indicator available but issues with interobserver reliability and biopsy sampling error fuel therapeutic indecision and likely lead to over- or under-treatment. Prostate cancer genomic testing takes several forms and offers additional information for predicting the clinical behavior of a tumor. Urine based assays take advantage of the prostate’s anatomic location in the urinary tract to look for genetic material that is associated with finding prostate cancer on a subsequent biopsy. Prostate biopsy tissue samples give direct access to the cancer genome and provide information beyond what is ascertainable using a microscope. If the Gleason score provides a snapshot of the current state of a given prostate tumor, then these tissues based genomic tests offer a window in its future. Several commercially available tests are currently available but only a small number have been FDA-approved thus far. Even the best products have only provided modest gains in prognostic accuracy over existing clinical risk stratification tools, however, this is a key step in the right direction that is nearly a decade behind other malignancies (i.e. breast). There is published data to suggest that these tests can alter physician practice patterns, but to what degree they will ultimately alter clinically significant outcomes remains to be seen.