High percent tumor volume predicts biochemical recurrence after radical prostatectomy in pathological stage T3a prostate cancer with a negative surgical margin

Objectives: To evaluate the impact of percent tumor volume and surgical margin status on biochemical recurrence in pT3-T4 prostate cancer.

Methods: A total of 397 patients who had pT3-T4N0 diseases and did not receive neoadjuvant or adjuvant therapy were included for analysis.

Results: In the entire cohort, prostate-specific antigen (per 1 ng/mL increase; hazard ratio 1.019; P = 0.002), pathological stage (T3b-T4 vs T3a; hazard ratio 2.283; P < 0.001), Gleason score (≥8 vs ≤6; hazard ratio 5.290; P = 0.005), surgical margin status (multiple positive vs negative; hazard ratio 1.839; P = 0.003) and lymphovascular invasion (present vs absent; hazard ratio 1.641; P = 0.008) were independent predictors of recurrence. Percent tumor volume was an independent predictor of recurrence in T3a diseases with negative surgical margins. In analysis using receiver operating characteristic curve, a threshold of 12% showed the best balance of sensitivity and specificity, 66% and 67%, respectively. The 5-year recurrence-free survival rates of pT3a diseases with negative surgical margin were 85.2% for percent tumor volume ≤12% and 57.7% for percent tumor volume >12% (P < 0.001). Patients with pT3a with negative surgical margins and percent tumor volume >12% showed comparable 5-year recurrence-free survival rate compared with those with pT3a with positive surgical margin (57.7% vs 57.6%; P = 0.763).

Conclusions: Despite having less impact on recurrence than other clinicopathological variables in pT3-T4 prostate cancer, percent tumor volume can further improve recurrence risk stratification in pT3a diseases with negative surgical margins.