The increasing incidence of prostate cancer, especially in this age group, which may be attributed in part to the more prevalent use of prostate-specific antigen (PSA) testing [3], has led to defining this distinct phenotype with higher cancer-specific mortality as early-onset prostate cancer (HR 1.22 [95% CI 1.10–1.49] compared to patients aged 60–69 years) [2]. Here, KLK3 is linked to prostate cancer.