Moreover, few prior studies have used appropriate decision analytic methods: analyses that focus on the 'diagnostic gray zone' (for example, PSA of 4 to 10 ng/ml) [6,41], or those that compare the specificity of PSA versus PSA plus free PSA at a fixed sensitivity (for example, 90%) [42,43] have a questionable theoretical bias because they use criteria chosen without clear reference to the relative harms of unnecessary biopsy compared with a missed cancer. The gene discussed is KLK3; the disease is cancer.