The results of Spearman’s rank correlation for the association of PSA with potentially explanatory variables (age, BMI, smoking habits and alcohol consumption, metal(loid) levels, parameters of oxidative stress) in prostate cancer patients showed a significant inverse relationship between blood Pb and PSA (R = −0.252, p = 0.012) when both cohorts were examined. This evidence concerns the gene KLK3 and prostate carcinoma.