A prospective study evaluating indirect MRI-signs for the prediction of extraprostatic disease in patients with prostate cancer: tumor volume, tumor contact length and tumor apparent diffusion coefficient

Objective The aim of this study was to evaluate three indirect MRI signs for predicting extraprostatic disease in patients referred to radical prostatectomy: index tumor volume (MTV), apparent diffusion coefficient (ADC) and tumor contact length (TCL). Materials and methods This prospective study included 183 patients with biopsy proven prostate cancer. In all patients the MTV (ml), ADC (× 10 −5 mm 2 /s) and TCL (mm) of the index tumor were registered at the preoperative MRI. Whole-mounted microscopical examination classified each patient as having either localized- or extraprostatic disease. The Youden index was used to identify the optimal cut-off values for predicting extraprostatic disease. Univariate regression analyses were conducted to estimate the odds ratio (OR) with 95% confidence intervals (CI). Results were stratified upon zonal location of the index tumor. Results Extraprostatic disease was identified in 103 (56%) patients. The risk of extraprostatic disease was nine times higher in peripheral zone tumors with ADC ≤ 89 (OR 9.1, 95% CI 4.2–19.6), five times higher in MTV ≥ 0.9 ml (OR 5.5, 95% CI 2.6–11.4) and five times higher in case of TCL ≥ 14 mm (OR 4.9, 95% CI 2.3–10.2). None of the indirect MRI signs could predict extraprostatic disease for transition zone tumors. Conclusion The MTV, ADC and TCL are all significant predictors of extraprostatic disease for peripheral zone tumors, while none of the indirect signs were useful for transition zone tumors.