PROSTASCINT(R) SCAN MAY ENHANCE IDENTIFICATION OF PROSTATE-CANCER RECURRENCES AFTER PROSTATECTOMY, RADIATION, OR HORMONE-THERAPY - ANALYSISOF 136 SCANS OF 100 PATIENTS

BACKGROUND. Primary extraprostatic spread or failure after prostate ca ncer treatment can occur locally in the prostatic fossa and/or metasta size to regional and/or distant lymphatics and/or in bone. We evaluate d the ability of the ProstaScint(R) (Cytogen Corp., Princeton, NS) sca n to identify soft tissue recurrence of prostate cancer in patients wh o failed primary treatment, and we monitored their responses to a seco ndary treatment. METHODS. The 111indium-labeled monoclonal antibody (P rostaScint(R)) was evaluated in a series of 136 consecutive scans asso ciated with a complete set of relevant clinical and biochemical data. These scans represented 100 patients, imaged between November 1994-May 1998, who underwent a definitive prostate cancer treatment followed b y evidence of recurrence. All patients had serum prostate-specific ant igen (PSA), Western-blot serum prostate-specific membrane antigen (PSM A), and bone scans. Prostatic fossa and/or lymph node biopsies were av ailable in 33 patients. RESULTS. Overall, no adverse reactions were re lated to any of the radioactive antibody infusions. The average age wa s 69 years (range, 48-89 years), serum PSA was 55.9 ng/ml (range, 0-2, 185 ng/ml), and serum PSMA was 0.32 (relative intensity levels range, 0.04-0.55). The initial therapies given were radical prostatectomy (55 scans), prostate radiation (74 scans), and/or hormonal therapy (77 sc ans). Twelve patients exhibited a negative scan. Local recur rence alo ne was identified in 58 scans (42.6%). Lymph node metastases were iden tified in 66 scans (48.5%). Of these, 21 had regional metastases alone , and 45 had distant lymph node metastases. Ten scans showed skip lymp h node metastases without regional failure. PSA significantly correlat ed with negative, pelvic, and extrapelvic scan findings (P less than o r equal to 0.02). PSMA correlated best with pelvic recurrence and extr apelvic metastases in prostatectomized patients. Thirty-four patients had repeated scans for monitoring treatment response. Of these patient s, 19 (56%) showed progression on the second scan, consistent with per sistent increase in PSA and PSMA levels in all but 2 patients. Another 11 patients showed no change, and 4 patients showed partial remission , suggesting a response to the salvage treatment. All 20 positive pros tate biopsies and 4 of the 7 positive lymph node biopsies correlated w ith ProstaScint(R) findings, whereas 4 of the 6 patients with a negati ve biopsy had negative scans (i.e., 89% sensitivity and 67% specificit y). Bone metastases were identified in 42 bone scans; 45% of these sho wed no lymph node metastasis on ProstaScint(R). In another 24 patients (57%), bone metastases were detected on ProstaScint(R) examinations. CONCLUSIONS. The ProstaScint(R) scan tracks the source of serum PSA or PSMA relapses after radical prostatectomy, radiation, and/or hormone therapy of prostate cancer. It may identify lymph node metastases or a local recurrence, and is not adversely affected by concurrent hormona l therapy. (C) 1998 Wiley-Liss, Inc.