Use of preoperative plasma endoglin for prediction of lymph node metastasis in patients with clinically localized prostate cancer.

PURPOSE: Current predictive tools and imaging modalities are not accurate enough to preoperatively diagnose lymph node metastases in patients with prostate cancer. The aim of the study was to evaluate whether preoperative plasma endoglin improves the prediction of lymph node metastases in patients with clinically localized prostate cancer. EXPERIMENTAL DESIGN: Endoglin levels were measured using a commercially available ELISA assay in banked plasma from 425 patients treated with radical prostatectomy and bilateral lymphadenectomy for clinically localized prostatic adenocarcinoma at two university hospitals between July 1994 and November 1997. Logistic regression analyses were undertaken to evaluate whether endoglin improves the accuracy of a standard preoperative model for prediction of lymph node metastasis and to build a predictive nomogram. RESULTS: Preoperative plasma endoglin levels were higher in patients with higher preoperative total serum prostate-specific antigen (PSA; Spearman correlation coefficient 0.296, P < 0.001), positive surgical margins (P = 0.03), higher pathologic Gleason sum (P = 0.04), and lymph node metastasis (P < 0.001). In a preoperative multivariable logistic regression analysis that included PSA and clinical stage, only preoperative endoglin (odds ratio, 1.17; 95% confidence interval, 1.09-1.26; P < 0.001) and biopsy Gleason sum (odds ratio, 18.57; 95% confidence interval, 1.08-318.36; P = 0.04) were associated with metastasis to lymph nodes. The addition of endoglin to a standard preoperative model (including PSA, clinical stage, and biopsy Gleason sum) significantly improved its accuracy for prediction of lymph node metastasis from 89.4% to 97.8% (P < 0.001). CONCLUSIONS: Preoperative plasma endoglin improves the accuracy for prediction of pelvic lymph node metastasis in patients treated with radical prostatectomy for clinically localized prostate cancer by a statistically and clinically significant margin.