Current applications of immunoscintigraphy in prostate cancer

While adenocarcinoma of the prostate has always been one of the top three lethal malignant diseases in adult men, the ever-increasing size of the older male population due to prolonged life expectancy has added to the importance of this condition. It is estimated that over 133,000 new cases of prostatic cancer will be diagnosed this year and some 34,000 men will die from the disease. Thus, the importance of early detection and accurate staging has become more critical, particularly since safe and effective treatments are available. There is still considerable debate as to the most effective means of detection and routine screening procedures for prostatic cancer in men over the age of 50 yr. Digital rectal examination, prostatic-specific antigen determinations and rectal ultrasonography are the most successful and cost-effective screening procedures available. Regardless of the technique used, simple, accurate and reproducible staging is essential. Total surgical removal of the prostate, whether by radical retropubic or perineal approach, along with a lymph node dissection, is a potentially curative procedure. This is true provided the clinical staging is accurate and no undetected metastatic lesions are present. It is in this latter area that current technology is lacking. Routine technetium bone scans are not specific for prostatic cancer. Similarly, abdominal/pelvic computed tomography studies fail to detect lesions in localized prostatic cancer. A tumor-specific scan that detect not only bony lesions but also soft-tissue lesions would be optimal. Some believe that monoclonal antibodies directed at tumor-specific antigens afford this opportunity. We report on the Phase 1 clinical study results using an indium-labeled conjugate of the 7E11-C5.3 murine monoclonal antibody in patients with prostate cancer.