MKI67 and prostate cancer: Ki67 proliferative index is an independent predictor of prostate cancer outcomes (Fisher et al., 2013; Pollack et al., 2004; Zellweger et al., 2009); however, the wide range of Ki67 expression naturally observed in clinical prostate tumors and a lack of consensus on appropriate cutoff points have prevented utilization of Ki67 as a marker in the clinic (Penault‐Llorca and Radosevic‐Robin, 2017).