Defining pathological variables to predict biochemical failure in patients with positive surgical margins at radical prostatectomy: implications for adjuvant radiotherapy.

OBJECTIVE To evaluate the utility of estimated tumour volume, number of positive surgical margins (PSMs), and margin location for predicting biochemical failure in patients with PSM, in an attempt to better risk-stratify the heterogeneous group of patients at high risk of biochemical failure after radical prostatectomy (RP) for prostate cancer. PATIENTS AND METHODS We reviewed our database of 2410 patients who had RP, and isolated 423 with PSMs who had a prostate-specific antigen (PSA) nadir at undetectable levels. Kaplan-Meier curves were used for univariate survival analysis, with the log-rank test used to examine differences between survival curves. Multivariate Cox regression analysis was used to assess the independent main effect of estimated tumour volume, number of PSMs and margin location on biochemical-free survival. RESULTS Increasing estimated tumour volume was directly associated with increasing risk of biochemical failure in patients with PSMs (P = 0.041). Patients with more than one PSM were at greater risk of biochemical failure than those with one PSM (P = 0.001). Margin location had no effect on biochemical-free survival in patients with PSMs. When incorporated into a multivariate Cox regression model including age, preoperative PSA level and pathological Gleason score, estimated tumour volume and number of PSMs remained independent predictors of biochemical recurrence. CONCLUSIONS Coupled with other variables before and after RP, both estimated tumour volume and number of PSMs might serve to further discriminate those patients most likely to benefit from immediate adjuvant radiotherapy after RP.