Correlations between Apparent Diffusion Coefficient and Gleason Score in Prostate Cancer: A Systematic Review

Reported data regarding the associations between apparent diffusion coefficient (ADC) of diffusion-weighted imaging (DWI) and Gleason score in prostate cancer (PC) are inconsistent. The aim of the present systematic review was to analyze relationships between ADC and Gleason score in PC. MEDLINE library, SCOPUS, and EMBASE databases were screened for relationships between ADC and Gleason score in PC up to April 2018. Overall, 39 studies with 2457 patients were identified. Data on the following parameters were extracted from the literature: number of patients, cancer localization, and correlation coefficients between ADC and Gleason score. Associations between ADC and Gleason score were analyzed by the Spearman's correlation coefficient. In overall sample, the pooled correlation coefficient between ADC and Gleason score was −0.45 (95% confidence interval [CI] = [−0.50; −0.40]). In PC in the transitional zone, the pooled correlation coefficient was −0.22 (95% CI = [−0.47; 0.03]). In PC in the peripheral zone, the pooled correlation coefficient was −0.48 (95% CI = [−0.54; −0.42]). In PC located in the peripheral zone, ADC correlated moderately with Gleason score. In PC located in the transitional zone, ADC correlated weakly with Gleason score. We reviewed studies using apparent diffusion coefficient for the prediction of Gleason score in prostate cancer patients.