Healthy aged-matched controls (HC) (n = 131) showed significant lower levels of PSA below 1 ng/mL (0.81 ± 0.5 ng/mL versus 10.46 ± 17.94 ng/mL, p-value = <0.0001) and were devoid of any cancer or other known comorbidities. This evidence concerns the gene KLK3 and cancer.