Postoperative early ultrasensitive prostate-specific antigen identifies patients at risk for biochemical recurrence in margin positive prostate cancers: a single-center study.

OBJECTIVE: To identify predictors for biochemical recurrence among patients with positive surgical margins (RM1) after radical prostatectomy and to examine the effect of ultrasensitive prostate-specific antigen measured early after prostatectomy on biochemical recurrence.

METHODS: We identified 705 patients with prostate cancer who were treated with radical prostatectomy without preoperative hormonal therapy at our institution between 2000 and 2014. The patients with RM1 who had a postoperative prostate-specific antigen <0.2 ng/ml without lymph node metastasis were evaluated for biochemical recurrence-free survival. Survival rates were calculated using the Kaplan-Meier method. The Cox regression model was used for multivariate analysis. The prediction of biochemical recurrence was assessed using area under the curve of the receiver operating characteristic.

RESULTS: Among the 705 patients, 190 (27%) had RM1. Biochemical recurrence was evaluated in 164 patients, excluding 26 patients who underwent adjuvant therapy with or without lymph node metastasis. With a median follow-up of 55 months, the biochemical recurrence-free survival rate of the entire RM1 cohort was 78% at 2 years and 64% at 4 years. The multivariate analysis revealed that postoperative early ultrasensitive prostate-specific antigen >0.02 ng/ml was the significant risk factor for biochemical recurrence (hazard ratio 13.10). Meanwhile, the patients with postoperative early ultrasensitive prostate-specific antigen <0.01 ng/ml had a significantly lower risk for biochemical recurrence (hazard ratio 0.12). Area under the curve for the postoperative early ultrasensitive prostate-specific antigen value to predict biochemical recurrence was 0.789.

CONCLUSIONS: The ultrasensitive prostate-specific antigen value measured early after prostatectomy was the potent predictor of biochemical recurrence among the patients with RM1.