Summary: We evaluated the prognostic value of the mitosis-associated marker phosphorylated histone H3 (PHH3) and Ki-67 in prostate cancer with respect to ERG status and androgen receptor (AR) expression.

PHH3 and Ki-67 expression was immunohistochemically detected and digitally quantitated in a radical prostatectomy cohort (n = 640). The results were correlated to clinicopathological parameters including biochemical recurrence times. Prognostic values of PHH3 and Ki-67 were analysed by Cox regression and Kaplan–Meier statistics.

In prostate cancer, mean Ki-67 and PHH3 rates were 3.40% (95%CI 3.16–3.63%) and 0.0152% (95%CI 0.0112–0.0191%), respectively.

Ki-67 showed a significant correlation with Gleason scores, pT status, margin status, and AR expression, while PHH3 showed a significant correlation with Gleason scores and pT status. Univariate analyses for biochemical recurrence times demonstrated a significant prognostic value for median Ki-67 rate and for the PHH3 rate of the 90th percentile. Of importance, in patient subgroups stratified according to AR expression and ERG translocation, the prognostic power of proliferation markers PHH3 and Ki-67 was markedly enhanced in ERG translocation negative and high-level AR expressing ERG translocation positive prostate cancers.

As expected, the proliferation markers PHH3 and Ki-67 predict adverse outcome of prostate cancer and have a particularly pronounced prognostic value in specific molecular subsets of prostate cancer (ERG− or AR+).