KLK3 and cancer: In fact, some studies have shown that only 22%–26% of men with elevated PSA levels (4.0–9.9 ng/mL) have cancer, hence PSA testing leads to large number of unnecessary prostate biopsies and emotional morbidity (Catalona et al., 1991; Brawer et al., 1992; Yamamoto et al., 2020; Bennett et al., 2022).