Radioimmunodetection of prostatic cancer: in vivo use of antibody against r-seminoprotein for diagnosis of prostatic cancer.

Forty patients (25 cases of prostatic cancer and 15 cases of benign prostatic hyperplasia) were examined with radioimmunodetection (RAID) using antibody against r-Seminoprotein (r-Sm). The images of malignant tumor sites were revealed from the scan of single photon emission computerized tomography with the tracing of dual radionuclide and computer digital subtraction technique. Of the 25 patients with prostatic cancer tested, twenty-four were demonstrated in RAID with a positive rate of 96%. The ratio of taking in nuclide radioactivity between the tumor tissue and normal tissue (T/N) was 6.9 and the best showing time was the 96th hr from injection of radioactive antibody against r-Sm. The minimum diameter of the tumor detected in RAID was 0.5 cm. All of the 8 cases of metastatic prostatic cancer in pelvic or bone location were detected, with a rate of 100%. Of the 15 cases of benign prostatic hyperplasia, only one showed mild positive result. B-ultrasonography and CT showed a positive detective rate of 72.7% and 65%, respectively. Our results have indicated that RAID using 131I-labeled antibody against r-Sm possesses more advantages in specificity, because RAID not only defines the involved sites, but also shows the sites of the original tumors, and the metastatic location as well as the relationship between them.