Emerging biomarkers for prostate cancer diagnosis, staging, and prognosis

The introduction and widespread adoption of PSA has revolutionized the way prostate cancer is diagnosed and treated. However, the use of PSA has also led to over-diagnosis and overtreatment of prostate cancer resulting in controversy about its use for screening. PSA also has limited predictive accuracy for predicting outcomes after treatment and for making clinical decisions about adjuvant and salvage therapies. Hence, there is an urgent need for novel biomarkers to supplement PSA for detection and management of prostate cancer. Despite the progress in developing new biomarkers, several obstacles remain before such biomarkers can be clinically used. These challenges include analytical and regulatory barriers, issues with study design and data analysis that lead to lack of reproducibility of promising results, and the lack of large scale trials to adequately assess the utility of promising biomarkers. In this article we discuss the challenges in biomarker research and the statistical considerations for biomarker evaluation. There is a plethora of promising blood and urine based biomarkers. For the purpose of this review, we focus on PSA derived forms, human kallikrein 2, Early Prostate Cancer Antigen, Transforming Growth Factor-Beta 1 and Interleukin-6, Endoglin, PCA3, AMACR and ETS Gene Fusions. These biomarkers have shown promise in early studies and are at various stages of development. However, in the future it is very likely that a panel of biomarkers will be used to achieve sufficient degree of certainty in order to guide clinical decisions. To be able to be used commercially such a panel will have to answer clinically relevant questions in a simple and cost-effective way.