Emerging biomarkers in the diagnosis of prostate cancer

Prostate cancer (PCa) is the second most common cancer in men worldwide. A large proportion of PCa are latent, never destined to progress or affect the patients' life. It is of utmost importance to identify which PCa are destined to progress and which would benefit from an early radical treatment. Prostate-specific antigen (PSA) remains the most used test to detect PCa. Its limited specificity and an elevated rate of overdiagnosis are the main problems associated with PSA testing. New PCa biomarkers have been proposed to improve the accuracy of PSA in the management of early PCa. Commercially available biomarkers such as PCA3 score, Prostate Health Index (PHI), and the four-kallikrein panel are used with the purpose of reducing the number of unnecessary biopsies and providing information related to the aggressiveness of the tumor. The relationship with PCa aggressiveness seems to be confirmed by PHI and the four-kallikrein panel, but not by the PCA3 score. In this review, we also summarize new promising biomarkers, such as PSA glycoforms, TMPRSS2: ERG fusion gene, microRNAs, circulating tumor cells, androgen receptor variants, and PTEN gene. All these emerging biomarkers could change the management of early PCa, offering more accurate results than PSA. Nonetheless, large prospective studies comparing these new biomarkers among them are required to know their real value in PCa detection and prognosis.