Follow-up ProstaScint (R) scans verify detection of occult soft-tissue recurrence after failure of primary prostate cancer therapy

BACKGROUND. A reliable imaging modality is required to uncover occult soft- tissue recurrence after failure of primary prostate cancer therapy. This re trospective study was done to evaluate the ability of the (111)Indium-label ed monoclonal antibody (ProstaScint(R)) scan in detection of prostatic bed recurrence and/or metastases to regional and/or distant lymph nodes. METHODS. One hundred sequential patients were evaluated with repeated Prost aScint(R) scans because of evidence of recurrence during the course of thei r disease. These 100 patients were followed closely from November 1994 and April 1999, and had concurrent bone scans and serum prostate-specific antig en (PSA) evaluations. They have had hormone therapy (n = 53) and/or experie nced a rising PSA after radical ppostatectomy (n = 38) or after radiation t herapy (n = 56). Scan images were scored 0-3, where score 0 = negative, sco re 1 = prostate bed uptake, score 2 = regional lymph node uptake, and score 3 = distant lymph node uptake. In each patient, the uptake of the follow-u p scan(s) was compared to that of the initial scan. RESULTS. The median age was 70 years (range, 45-87), and 23 patients had a positive bone scan. The average PSA was 40.5 ng/ml (standard deviation, 223 .5). There was 257 scans representing 100 patients. All patients had at lea st 2 scans, 35 patients had 3 scans, and 11 patients had 4 scans. No indivi dual exhibited detectable adverse clinical reactions during or after the sc an. The findings of the initial and consecutive scans were anatomically con sistent in 79%, whereas in 21% there were skip metastases. In 24 patients t he lesions progressed by scan and PSA, 10 patients showed progression of sc an but no PSA progression, 49 patients showed no change, and 17 patients sh owed a remission related to adjuvant therapy. CONCLUSIONS, The consistency on repeating the scan (79%) and the high perce ntage of patients showing persistent uptake at the prostate bed (43%) as we ll as the percentage of detection of regional nodes (20%) and distant nodes (32%) reflects the importance of using the ProstaScint(R) scan in finding occult recurrences after primary treatment failure of prostate cancer. Thes e results are similar to those reported earlier in autopsy series studies i n similar populations. Prostate 42:315-317, 2000. (C) 1000 Wiley-Liss, Inc.