0022-5347/98/1604-1387$03.00/0 THE JOURNAL OF UROLOGY Copyright Q 1998 by AMEMCAN UROUX~ICAL AS~OCIATION, INC. Vol. 160. 1387-1391, October 1998 Printed in USA LIMITED ROLE OF RADIONUCLIDE BONE SCINTIGRAPHY IN PATIENTS WITH PROSTATE SPECIFIC ANTIGEN ELEVATIONS AFTER RADICAL PROSTATECTOMY MICHAEL L. CHER, FERNANDO J. BIANCO, JR., JOHN S. LAM, LAWRENCE P. DAVIS, DAVID J . GRIGNON, WAEL A. SAKR, MOUSUMI BANERJEE, J. EDSON PONTES, AND DAVID P. WOOD, JR. From the Departments of Urology, Radiology and Pathology, Wayne State University School of Medicine and Progmm in Genitourinary Oncology, Karmanos Cancer Institute, Detroit, Michigan ABSTRACT Purpose: Bone scintigrams of patients with increasing serum prostate specific antigen (PSA) after radical prostatectomy are only rarely positive. We identify clinical parameters that would improve our ability to select patients for this imaging study. Materials and Methods: We reviewed all bone scintigrams done at our institution between 1991 and 1996 in patients with persistently increasing serum PSA after radical prostatectomy. What prompted the clinician to obtain the bone scintigram was trigger PSA (tPSA).The rate of increase in PSA to tPSA was measured by tPSNtime from radical prostatectomy (slope 1) and tPSNtime from last undetectable PSA (slope 2). These parameters were evaluated together with standard clinicopathological data in univariate and multivariate analyses to determine the ability to predict the bone scintigram result. Results: In univariate analysis tPSA (p = 0.003), slope 1 (p = 0.005) and slope 2 (p = 0.004) were useful in predicting the bone scintigram result but pathological stage, Gleason score, preoperative PSA and time to recurrence were not. In multivariate analysis the single most useful parameter in predicting the bone scintigram result was tPSA (p = 0.01). Based on a logistic regression model the probability of a positive bone scintigram was less than 5% until tPSA increased to 40 to 45 ngJml. Conclusions: In patients with increasing serum PSA after radical prostatectomy current serum PSA is the best predictor of the bone scintigram result. Furthermore, there is limited usefulness of bone scintigraphy until PSA increases above 30 to 40 ng./ml. KEY WORDS: bone and bones, radionuclide imaging, prostatedomy, prostate-specific antigen The optimal evaluation of patients with increasing serum prostate specific antigen (PSA) after definitive local therapy has not been determined. Patients with increasing serum PSA after radical prostatectomy are assumed to have persis- tent or recurrent disease. These treatment failures can be categorized as local and/or distant recurrence. Currently the inability to distinguish between these types of treatment failures makes management decisions difficult. Frequently radionuclide bone scintigraphy is used to screen for meta- static disease in patients with increasing serum PSA after radical prostatectomy but this test is only rarely positive. A significant proportion of patients with increasing PSA after radical prostatectomy will eventually have metastatic dis- ease.' However, bone scintigraphy is unable to image small volumes of metastatic tumor that are detected by serum PSA. Thus, although patients may have metastatic disease that Will eventually become clinically detectable, bone scintigra- phy is unlikely to be a cost-effective diagnostic tool. We evaluate more systematically the role of radionuclide bone Schtigraphy as a screening test for metastatic disease in Patients with increasing serum PSA after radical prostatec- tomy. MATERIALS AND METHODS We performed a retrospective review of all radionuclide bone scintigrams done at our institution between January 1993 and December 1996 in patients with inmasing serum Accepted for publication May 8,1998. PSA after radical prostatectomy. Bone scintigrams were done after intravenous administration of 25 to 30 mCi. 99"techne- tium methylene diphosphonate. Total body images were ob- tained 242 to 3 hours after injection. All bone scintigrams were interpreted by nuclear radiologists. Analysis was per- formed to predict the probability of a positive bone scinti- gram. Therefore, a bone scintigram was counted as positive only if the results were unequivocal or immediate additional imaging demonstrated unequivocal metastasis. Clinicopathological information was obtained from the Karmanos Cancer Institute prostate database, which con- tains detailed information on all patients treated with radi- cal prostatectomy at our institution since 1991. All patients had clinically localized disease and underwent radical retro- pubic prostatectomy with bilateral pelvic lymph node dissec- tion. The radical prostatectomy specimen was examined as described previou~ly.~.~ Patients were considered to have disease recurrence at the time of first detectable serum PSA as long as serum PSA continued to increase on subsequent assays. Cases with detectable or increasing serum PSA levels within 3 months of surgery were categorized as immediate failures at the date of surgery. The serum PSA assay that prompted the clinician to obtain a bone scintigram was trig- ger PSA (tPSA) (fig. 1). The rate of increase in serum PSA (ngJml. per month) to tPSA was measured by tPSA divided by the time since surgery (slope 1) and tPSA divided by the time since last undetectable serum PSA (slope 2). For pa- tients who never had undetectable PSA surgery date was the starting point and, thus, tPSA slopes 1 and 2 were equal. 1387