KLK3 and neoplasm: In free PSA predominant patients, compared to patients with α1-antichymotripsin bound PSA as the predominant molecular form, the ratio of well- differentiated tumours were significantly higher (P=0.014); the ratios of T1–T2 tumours (P=0.052) and early stage disease (stages I and II) (P=0.090) were slightly higher.