Prostate cancer is second only to lung cancer as the leading cause of cancer deaths in American men. In 1997, approximately 209,900 new cases of prostate cancer were diagnosed, and more than 41,800 deaths were attributed to this malignancy (1). Primary or recurrent prostate cancer can be curatively treated when it is confined to the gland. The therapy of choice is radical prostatectomy. Therefore, curative treatment for localized tumors may be the best hope for lowering the mortality rate of prostate cancer (2). If the tumor has spread beyond the gland, chemotherapy, immunotherapy, or hormonal therapy are at present used. However, metastatic prostate cancer cannot be cured with these modalities. According to this viewpoint, it is clear that the primary focus of prostate cancer management should be the detection and aggressive treatment of tumors while they are still confined to the prostate.

A great step forward was the discovery of prostate-specific antigen (PSA), which has made possible the detection of tumors before they become palpable on rectal examination. In general, diagnosis of primary or recurrent prostate tumors is based on clinical examination, PSA level, and radiologic imaging modalities such as ultrasound, CT, and MRI. When PSA testing is used alone, it can detect up to 80% of prostate cancers. However, the PSA test lacks specificity, since only one third of men with an abnormal serum PSA level actually have cancer (3). The task of nuclear medicine is to en-