Comparison of helical computerized tomography, positron emission tomography and monoclonal antibody scans for evaluation of lymph node metastases in patients with prostate specific antigen relapse after treatment for localized prostate cancer

Purpose: We compare the detection of metastatic disease by helical computer ized tomography (CT), positron emission tomography (PET) with F-18 fluorode oxyglucose and monoclonal antibody scan with (111)indium capromab pendetide in patients with an elevated prostate specific antigen (PSA) after treatme nt for localized prostate cancer. Materials and Methods: A total of 45 patients with an elevated PSA (median 3.8 ng./ml.) were studied following definitive local therapy with radical p rostatectomy in 33, radiation therapy in 9 and cryosurgery in 3. CT of the abdomen and pelvis, and whole body PET were performed in all patients, of w hom 21 also underwent monoclonal antibody scan. Lymph nodes 1 cm. in diamet er or greater on CT were considered abnormal and were sampled by fine needl e aspiration in 12 patients. Results: PET and CT were positive for distant disease in 50% of 22 patients with PSA greater than 4, and in 4 and 17%, respectively, of 23 with PSA le ss than 4 ng./ml. The detection rate for metastatic disease was similar for CT and PET, and higher overall than that for monoclonal antibody scan. Mon oclonal antibody scan was true positive in only 1 of 6 patients, while PET was true positive in 6 of 9 with CT guided fine needle aspiration proved me tastases. Conclusions: CT and PET each detected evidence of metastatic disease in 50% of all patients with a high PSA or PSA velocity (greater than 4 ng./ml. or greater than 0.2 ng./ml, per month, respectively). Bath techniques are lim ited for detecting metastatic disease in patients with a levy PSA or PSA ve locity. Our data suggest that monoclonal antibody scan has a lower detectio n rate than CT or PET.