IGFBP2 as an immunohistochemical marker for prostatic adenocarcinoma

The aim of the study was to evaluate the immunohistochemical expression of insulin-like growth factor binding protein 2 (IGFBP2) in normal epithelium, high-grade prostatic intraepithelial neoplasia (HG-PIN), and prostatic adenocarcinoma (PAc), in patients hormonally untreated and in those having undergone complete androgen ablation.

IGFBP2 expression was evaluated in PAc, HG-PIN, and normal-appearing epithelium in 40 radical prostatectomies from hormonally untreated patients and 10 radical prostatectomies from patients under complete androgen ablation before surgery. The study also included the initial biopsies of such patients, and an additional 10 simple prostatectomies from patients with bladder outlet obstruction. Statistics included receiver-operator characteristic curves, the Wilcoxon test, and the Spearman test. Results were compared with α-methylacyl-CoA racemase.

The principal findings were: (1) IGFBP2 was not expressed in normal ducts and acini of the transition and peripheral zones; (2) IGFBP2 was expressed in the cytoplasm of untreated PAc and, to a lesser extent, in HG-PIN; (3) it was also expressed in PAc and HG-PIN after complete androgen ablation, but to a lesser extent than in the untreated neoplasms; (4) α-methylacyl-CoA racemase was expressed both in PAc and HG-PIN, the level being similar in both lesions and lower in the specimens from the patients having undergone androgen ablation.

Results obtained show that IGFBP2 is expressed in invasive PAc, whereas its expression in HG-PIN is low. These findings can be helpful in the correct diagnosis of PAc both in biopsies and in surgical specimens, mainly in untreated patients.