To investigate the relationship between prostate volume measured from preoperative imaging and adverse pathologic features at the time of radical prostatectomy and evaluate the potential effect of clinical stage on such relationship.

In 1756 men who underwent preoperative magnetic resonance imaging and radical prostatectomy from 2000 to 2010, we examined associations of magnetic resonance imaging-measured prostate volume with pathologic outcomes using univariate logistic regression and with postoperative biochemical recurrence using Cox proportional hazards models. We also analyzed the effects of clinical stage on the relationship between prostate volume and adverse pathologic features via interaction analyses.

In univariate analyses, smaller prostate volume was significantly associated with high pathologic Gleason score (P <.0001), extracapsular extension (P <.0001), and positive surgical margins (P = .032). No significant interaction between clinical stage and prostate volume was observed in predicting adverse pathologic features (all P >.05). The association between prostate volume and recurrence was significant in a multivariable analysis adjusting for postoperative variables (P = .031) but missed statistical significance in the preoperative model (P = .053). Addition of prostate volume did not change C-Indices (0.78 and 0.83) of either model.

Although prostate size did not enhance the prediction of recurrence, it is associated with aggressiveness of prostate cancer. There is no evidence that this association differs depending on clinical stage. Prospective studies are warranted assessing the effect of initial method of detection on the relationship between volume and outcome.