Whether population-based prostate MRI screening, analogous to mammography for breast cancer, can be clinically effective and cost-effective is being assessed in studies such as Goteborg-2.68 This study is testing three different screening approaches: PSA-based only (concentrations ≥3 ng/mL prompt biopsy), PSA concentrations of at least 3·0 ng/mL and abnormal MRI results are necessary to do a biopsy, or PSA concentrations of at least 1·8 ng/mL and abnormal MRI results prompt biopsy. The gene discussed is KLK3; the disease is breast carcinoma.