PET stands for positron emission tomography. It’s usually combined at the same time with CT (computerized tomography) to improve the quality of the images and help localize abnormalities. PET employs a slightly radioactive tracer drug that homes in on the targeted tissue. PET/CT scans work well for breast, lung, colon and other cancers, but until recently did not work well for prostate cancer because there were no effective tracer drugs for the disease. That changed on May 27, 2016, when the U.S. Food and Drug Administration approved a new PET scan tracer drug specifically for prostate cancer.
The drug is a synthetic amino acid analog called Axumin™ (fluciclovine F-18). Attached to the amino acid is a radioactive tracer, fluorine-18. After Axumin™ is injected into the patient, the drug is taken up by prostate cancer cells. The fluorine-18 emits a small amount of energy in the form of gamma rays. The PET/CT scanner detects this energy, and a computer produces a detailed image.
Two studies helped the Axumin™ PET Scan obtain its FDA approval. In one study, results from the Axumin PET Scans were compared with biopsy pathology, and read by several radiologists independent of each other.
The second study compared the Axumin™ PET Scan to the C11 Choline PET Scan, which is currently available at the Mayo Clinic. Patients in this study had a median PSA of 1.44. (Median is the middle number, not the average number.) Again, several radiologists read the scans independently and reported their findings. Based on these 2 studies, the FDA ruled that the Axumin™ PET Scan was both safe and effective.
Clearly this PET imaging could help fill a space where prostate cancer patients and their doctors are trying to make a treatment decision after surgery, and perhaps considering salvage radiation. It may help some men make a decision on spot radiation or surgical removal of a lymph node in the setting of a rising PSA. It may also help a patient make the decision to start hormone therapy, or other systemic treatments, instead of a more localized therapy. These are all issues to research, and discuss with your doctors, but they are some of the possible scenarios where this PET Scan may be helpful.
The scan can detect the location and extent of cancer that has recurred after initial treatment and spread to other parts of the body. Prostate PET/CT scans can detect cancer earlier than either CT scans alone or MRI scans.