Value of prostate-specific antigen measurements in predicting lymph node involvement in prostatic cancer.

The preoperative serum levels of prostate-specific antigen (PA) were determined in 35 consecutive patients who had clinically localized prostatic cancer and underwent bilateral staging pelvic lymphadenectomy. When 10.0 ng/ml of PA was used as the cutoff value for lymph node staging the specificity of an elevated PA level in revealing lymph node involvement was 77% with a sensitivity of 85% and an accuracy of 80%. Only 1 of 18 (6%) patients with negative PA levels (below 10 ng/ml) and a preoperative Gleason score 2-7 tumor had metastatic lymph node disease. Among the 17 patients with positive PA levels (above 10 ng/ml) or a Gleason score 8-10 tumor, 12 (71%) had lymph node involvement. The preoperative PA level and the extent of local tumor invasion correlated strongly with each other. Our study suggests that the PA level could be a simple and objective parameter with which to predict metastatic lymph node disease if used in conjunction with the Gleason histological grade.