KLK3 and cancer: This study suggests that when screening the general population for prostate cancer, MRI using a score of 4 or 5 to define a positive test result, compared with PSA testing alone at a level of 3 ng/mL or higher, might lead to more men being diagnosed with clinically significant cancer, without increasing the number of men advised to undergo biopsy or overdiagnosed with clinically insignificant cancer.