The depth of the prostatic apex is an independent predictor of positive apical margins at radical prostatectomy.

OBJECTIVE: To determine the effect of a deep and narrow pelvis on apical positive surgical margins (PSM) at radical prostatectomy (RP), controlling for other clinical and pathological variables and surgical approach, i.e. open retropubic (RRP) vs laparoscopic (LRP), as apical dissection is expected to be more challenging at RP with a prostate situated deep in a narrow pelvis.

PATIENTS AND METHODS: From July 2003 to January 2005, 512 consecutive patients with preoperative prostate magnetic resonance imaging (MRI) underwent RRP or LRP with no previous radio- or hormonal therapy. An additional 74 patients with preoperative MRI undergoing RP from December 2001 to June 2007 who had an apical PSM were also included, with 586 patients comprising the study population. Bony and soft-tissue pelvic dimensions, including interspinous distance (ISD), bony (BFW) and soft tissue (SW) pelvic width, apical prostate depth (AD) and symphysis pubis angle, were measured on preoperative MRI. The pelvic dimension index (PDI), bony width index (BWI) and soft-tissue width index (SWI) were defined as ISD/AD, BFW/AD and SW/AD, respectively. Multivariate logistic regression was used to assess the effect of pelvic dimensions on apical PSM, controlling for surgical approach and clinical and pathological variables.

RESULTS: There was no significant difference in ISD, BFW, SW or symphysis angle between patients with and without apical PSM. The AD was significantly greater in men with an apical PSM and consequently PDI, BWI and SWI were significantly lower in men with an apical PSM. Each of PDI, AD, BWI and SWI was a significant independent predictor of apical PSM, independent of surgical approach, and other clinicopathological variables. The main limitations of the study were that it was retrospective, and the relatively few patients with apical PSM.

CONCLUSIONS: Apical prostate depth is an independent risk factor for apical PSM at RP. MRI pelvimetry might allow for preoperative planning of the approach to RP.