INTRODUCTION: Our goal was to examine to what extent tumour volume (TV) and percentage of high grade tumour volume (%HGTV) affect the rate of positive surgical margins and the rate of biochemical recurrence after radical prostatectomy. MATERIALS AND METHODS: TV and %HGTV were routinely planimetrically quantified in a cohort of 780 consecutive patients. Mean follow-up was 46.7 months. Multivariable regression models addressed two separate endpoints: positive surgical margins and biochemical recurrence. The increase in model predictive accuracy related to the addition of TV and %HGTV to radical prostatectomy stage and grade was assessed, after 200 bootstrap resamples to reduce overfit bias. RESULTS: In multivariable logistic regression models addressing positive surgical margins rate, predictive accuracy increased by 1.9% (p
