Multifocal High Grade Prostatic Intraepithelial Neoplasia is a Significant Risk Factor for Prostatic Adenocarcinoma

Purpose: There is debate in the literature on the role of high grade prostatic intraepithelial neoplasia as a risk factor for subsequent prostatic adenocarcinoma detection on prostatic needle biopsy. We determined whether high grade prostatic intraepithelial neoplasia on initial prostatic needle biopsy is an independent risk factor for prostatic adenocarcinoma and whether differences exist between prostatic adenocarcinoma in patients with previous high grade prostatic intraepithelial neoplasia and those with a benign diagnosis. Materials and Methods: Pathological findings in prostatic needle biopsies in 12,304 men who underwent initial prostatic needle biopsy in an 8-year period were analyzed. Patients were included in the analysis when the initial diagnosis was high grade prostatic intraepithelial neoplasia alone or a benign diagnosis and at least 1 followup prostatic needle biopsy was performed. The primary study outcome was prostatic adenocarcinoma and secondary outcome measurements were cancer characteristics, such as Gleason score and extent of tissue involvement with prostatic adenocarcinoma. Results: In the high grade prostatic intraepithelial neoplasia group of 564 patients and the benign group of 845, 27.48% and 22.01%, respectively, were diagnosed with prostatic adenocarcinoma on followup prostatic needle biopsy (p = 0.02). When age, prostate specific antigen and sampling extent were adjusted for, the adenocarcinoma risk after an initial diagnosis of high grade prostatic intraepithelial neoplasia remained significant (OR 1.38, p = 0.03). The risk was related to the extent of high grade prostatic intraepithelial neoplasia in the initial sample with a greater likelihood of adenocarcinoma when multiple prostatic sites were involved by high grade prostatic intraepithelial neoplasia. Patients in whom prostatic adenocarcinoma developed after a benign diagnosis on initial prostatic needle biopsy had greater tumor volume. However, mean followup was longer in the benign group than in the high grade prostatic intraepithelial neoplasia group (2.35 vs 1.36 years). Conclusions: Patients with an initial diagnosis of high grade prostatic intraepithelial neoplasia, especially when multifocal, are at greater risk for subsequent prostatic adenocarcinoma than those with a benign diagnosis. Results suggest that followup should be more rigorous in patients with multifocal high grade prostatic intraepithelial neoplasia.