Predictors of pathological upgrading in low-risk prostate cancer patients without hypointense lesions on an apparent diffusion coefficient map of multiparametric magnetic resonance imaging

Purpose To examine the clinicopathological features and identify the predictors of pathological upgrading in low-risk prostate cancer (PCa) patients without hypointense lesions on the apparent diffusion coefficient (ADC) map calculated from multiparametric magnetic resonance imaging. Methods We reviewed the medical records of 1905 PCa patients who underwent radical prostatectomy between 2007 and 2015. All ADC images were graded using the five-grade Likert scale; the positive hypointense lesions were graded 4–5. We analyzed 256 patients with low-risk classifications according to D’Amico criteria. Patients were classified into two groups according to the pathologic upgrading in the surgical specimens. The predictive factors for pathologic upgrading were evaluated using a multivariate logistic regression analysis. Results In 256 patients with low-risk PCa, the percentage of positive cores [odds ratio (OR) 1.09; 95 % confidence interval (CI) 1.02–1.16], the percentage of cancer in the positive cores (OR 1.07, 95 % CI 1.03–1.12), and the presence of hypointensity on an ADC map (OR 2.28; 95 % CI 1.23–4.22) were independent predictors of pathologic upgrading. Notably, 138 of low-risk patients (53.9 %) had no hypointense lesions on an ADC map. Of these 138 patients, the percentage of positive cores (OR 1.09; 95 % CI 1.01–1.18) and the percentage of cancer in the positive cores (OR 1.06; 95 % CI 1.01–1.12) remained independent predictors of pathologic upgrading. Conclusions In low-risk PCa patients without hypointense lesions on an ADC map, biopsy-related parameters such as the percentage of positive cores and the percentage of cancer in the positive cores were independent predictors of pathological upgrading following radical prostatectomy.