MKI67 and prostate cancer: The subgroups defined by using the median PSA score and the highest quartile for Ki67 as cut-offs were related to standard prognostic markers such as Gleason score, tumor stage, and presence of metastases, but they also showed additional prognostic value and diverse biological characteristics similar to those recently described for the three molecular subgroups of prostate cancer [1, 2] and prostate cancer bone metastases [6, 7].