PREDICTED AND ACTUAL CHANGE IN SERUM PSA FOLLOWING PROSTATECTOMY FOR BPH

Objective. To determine the relationship between prostatic adenoma vol ume and serum prostate-specific antigen (PSA) levels in patients with benign prostatic hyperplasia (BPH), and to compare the predicted chang e in serum PSA following prostatectomy with the actual change observed . Methods. Transrectal ultrasound (TRUS) estimation of prostatic adeno ma (transition zone) and total gland volumes were calculated in 96 pat ients prior to prostatectomy. BPH was confirmed histologically followi ng transurethral prostatectomy (in 86) and open prostatectomy (in 10). Serum PSA was measured preoperatively in all patients and postoperati vely in 87 patients. Results. Correlation coefficients of 0.607 and 0. 614 were observed between PSA and adenoma and total gland volumes, res pectively. The geometric mean ratio of PSA to adenoma volume was 0.120 mug/L/cc with 95% Cl (0.104, 0.139) and to total gland volume was 0.0 68 mug/L/cc with 95% Cl (0.058, 0.078). TRUS-determined adenoma and to tal gland volumes correlated well (r = 0.915), as did TRUS-determined adenoma volume and resected weight (r = 0.878). The mean ratio of chan ge in PSA to resected weight was -0.096 mug/L/g with 95% Cl (-0.128, - 0.064). Neither total gland volume nor operation type affected the rel ationship between change in serum PSA and resected weight. Conclusions . The adenoma should be the main determinant of serum PSA levels in pa tients with BPH. TRUS adenoma volume measurement is therefore the most appropriate preoperative measure when one is interpreting elevated le vels of serum PSA in men thought clinically to have BPH.