A study conducted by researchers at Duke University and Johns Hopkins Medical Centers and published in the journal Cancer (94:987-996) found that the use of indium-111-capromab pendetide (ProstaScint), a radiolabeled monoclonal antibody imaging agent, allowed identification of recurrent prostate cancer earlier than conventional imaging methods, such as the computed tomography (CT) scan. Prostate cancer recurs in nearly 40% of patients, and about 11% are at high risk for metastatic spread of the disease. Conventional imaging methods are often only able to detect a more advanced stage of prostate cancer.
These findings could have a significant effect on treatment. For example, patients whose cancer is localized might be able to avoid undergoing a full course of chemotherapy. If the cancer has metastasized, some patients could avoid unnecessary surgery or radiation therapy as well as the side effects that often accompany these treatments, such as incontinence and erectile dysfunction.
The multicenter study led by Ganesh V. Raj, MD, PhD, from the Division of Urology, Duke University Medical Center, involved 255 men, who, after undergoing a radical prostatectomy, received no additional therapy and subsequently had an increase in their prostate-specific antigen (PSA) levels as the only indication that their cancer had recurred. These patients, whose PSA levels ranged from 0.1 to 4.0 ng/mL, then underwent capromab pendetide immunoscintigraphy to localize their disease.
The scan identified recurrent disease in 72% of patients with a PSA ≤ 4.0 ng/mL. Of 151 patients who underwent additional studies, bone and/or CT scans identified recurrence in 12% (16/139) and 16% (15/92) of patients, respectively.
"In most instances, conventional imaging modalities such as a CT scan detect a recurrence of prostate cancer only when a volume of cancer effects changes to normal anatomic structures, which also indicates a significant advance in disease progression," said Dr. Raj. "This study suggests that a ProstaScint scan may detect and localize recurrent prostate cancer earlier than previously thought possible for patients with a low serum PSA after radical prostatectomy."