In clinical practice, at the time of its introduction, PCA3 did not serve as a key marker of prostate cancer, but usually as an additional ancillary marker in the context of diagnostic confusion, e.g., when considering primary prostate biopsy or rebiopsy (especially at a time when magnetic resonance imaging (MRI) of the prostate was not as widespread and available in daily practice as it is today). The gene discussed is PCA3; the disease is prostate cancer.