New imaging tool, better prostate scan

US researchers say a novel, non-invasive imaging tool can measure prostate-specific antigen in prostate cancer models and visualize bone metastasis. Michael J. Evans, a research fellow at Memorial Sloan-Kettering Cancer Center in New York and colleagues said if further validated, the use of this tool -- a prostate cancer-specific radiotracer -- could potentially aid in treatment planning on an individualized patient basis. A radiotracer is a small amount of a compound that has been "tagged" with a radionuclide. Patients are injected with the radiotracer, which aids in visualizing the tumor using positron emission tomography. Evans and colleagues examined the effects of 89Zr-5A10, the first radiotracer designed specifically to target free PSA, a known biomarker of prostate cancer that provides a more accurate measure of risk when compared with serum PSA. "Once injected, the use of 89Zr-5A10 allows physicians to measure different biological properties among metastatic lesions within the same patient, which a serum biomarker cannot achieve," Evans said in a statement. The researchers tested the utility of 89Zr-5A10 in a group of male mice with PSA-positive prostate cancer. The study published in the journal Cancer Discovery found the radiotracer also helped researchers identify metastatic bone lesions related to the primary prostate cancer -- traditional bone scans are unable to discriminate between malignant and non-malignant lesions.