Seminal fluid: A useful source of prostate cancer biomarkers?

Prostate cancer (PCa) is the most common internal cancer in men, and is normally diagnosed at a localized stage through a combination of serum prostate-specific antigen (PSA) testing and digital rectal examination. However, PSA is not specific to PCa, with more than half the patients who have an elevated PSA test result having a negative nontargeted biopsy [1]. Moreover, because PCa is highly heterogeneous and often multifocal in nature, current diagnostic pathways result in extensive over-detection of indolent tumors not requiring treatment and, ironically, under-detection of aggressive low-volume tumors. These issues have contributed to conflicting recommendations for PSA-based detection from government and professional bodies. Multiparametric MRI is being increasingly used to localize and stratify prostatic lesions according to likelihood of significant PCa, which enables selective biopsying of patients. However, multiparametric MRI is expensive and fails to detect approximately 10% of significant tumors [2]. Thus, the need for a noninvasive and inexpensive test that accurately detects PCa and, more importantly, differentiates indolent from life-threatening PCa is urgently required.

Seminal fluid (SF) is composed of secretions from glands in the male urogenital tract: approximately 40% of SF is prostatic material, released following global smooth muscle contraction and expulsion into the urethra, with the remainder contributed by the seminal vesicles and testes. In this editorial, we will present a case for the potential of SF as a clinically relevant ‘liquid biopsy’ of the prostate that could assist in diagnosis of PCa.