Histopathological variables and biomarkers enhancer of zeste homologue 2, Ki-67 and minichromosome maintenance protein 7 as prognosticators in primarily endocrine-treated prostate cancer

Abstract

Objective: • To evaluate the prognostic value of histopathological variables and immunostainings of biomarkers enhancer of zeste homologue 2 (EZH2), Ki-67 and minichromosome maintenance protein 7 (MCM7) from core biopsies of hormonally treated patients with prostate cancer.

Patients and methods: • Biopsies of 247 primarily endocrine-treated patients were analysed for histopathological characteristics and Gleason scores (GS) according to the revised guidelines of International Society of Urologic Pathology (ISUP) consensus conference 2005. • Immunohistochemical stainings were analysed with the aid of digital image analysis. • The prognostic value of the histopathological variables and the biomarkers was analysed with univariate and multivariate Cox regression analysis, with biochemical recurrence as an endpoint.

Results: • Biomarkers EZH2 (relative risk [RR] 2.0, 95% confidence interval 1.2-3.3), Ki-67 (3.4, 2.1-5.5) and MCM7 (2.4, 1.5-3.9) were significantly associated with progression-free survival in a univariate analysis. • Ki-67 immunostaining index detected high-risk patients with GS of 7 (9.1, 8.0-10.3). • In a multivariate analysis with non-conventional GS groups 5-7 (3 + 4), 7(4 + 3)-8, and 9-10, the independent prognostic markers were pretreatment GS (2.2, 1.5-3.2), prostate-specific antigen (PSA) level (2.1, 1.1-4.2), perineural invasion (PNI) (1.6, 1.2-2.2), and clinical T-stage (cT) (1.9, 1.0-3.7). • Combination of the independent markers (PSA level > 20 ng/mL or GS >3 + 4 or PNI >3 or cT >2) yielded best risk stratification (RR 11.6, 10.4-12.7).

Conclusions: • GS remains one of the most important prognostic factors in prostate cancer. However, the refined guidelines by ISUP 2005 might have shifted the threshold between low-grade and high-grade cancers from GS 6 vs 7 to GS 3 + 4 vs 4 + 3. • PNI is an independent prognostic marker superior to cT. • Ki-67 is the most useful biomarker in detecting patients with GS = 7 at high risk for progression.