Age and site-specific variations in KI-67 expression in peripheral zone lesions of the prostate: A prospective observational study

Background

Prostatic adenocarcinoma predominantly originates within the peripheral zone (PZ), and its biologicalbehaviour is influenced by patient age as well as the anatomical location of the tumour within the gland. Ki-67, a nuclearproliferation-associated antigen detectable only in actively cycling cells, enables quantification of tumour cell proliferativeactivity by immunohistochemistry.[2,3,7] Prospective evidence delineating how Ki-67 expression is modulated by age andbiopsy subsite within the prostatic PZ remains limited. The objective is to evaluate age- and site-specific differences in Ki-67labeling index (LI) in peripheral zone lesions of the prostate, to correlate Ki-67 with clinicopathological parameters (PSA,Gleason score, tumour stage), and to identify anatomical hotspots of elevated proliferative activity. Materials and Methods:A prospective observational study was conducted from August 2022 to August 2025 in the Department of Pathology at atertiary care hospital. Sixty patients who underwent transrectal ultrasound (TRUS)-guided site-mapped biopsies from six PZsubsites (right/left base, mid, apex) were enrolled. Ki-67 LI was calculated as the percentage of positively stained nucleiamong ≥500 lesional cells per core. Statistical associations were evaluated using one-way ANOVA with post-hoc Tukey testand the Kruskal–Wallis test, with p<0.05 considered significant.