Bone scans, computed tomography (CT), and magnetic resonance imaging (MRI) are imaging tests used to assess the spread of cancer in the body and to determine whether anticancer treatments are working. Even with these tests, however, it is sometimes difficult to find exactly where the cancer is located and to determine whether it is growing or shrinking in response to treatment. This difficulty is particularly apparent in patients with advanced prostate cancer that has spread to the bones, as standard CT, MRI, as bone scans are not accurate in assessing cancer in the bones.
In this study, investigators at Memorial Sloan-Kettering Cancer Center are evaluating positron emission tomography (PET) scanning in patients with advanced prostate cancer. They want to determine if PET scans may be better able to find places in the body where prostate cancer may have spread, and if it can detect responses to treatment earlier and more accurately than standard imaging studies.
PET scanning uses a substance called a “radiotracer” to tell how active a tumor is and where it is located. A radiotracer is a drug that carries a small amount of radiation that can be seen on the scan. Two radiotracer drugs will be used in this study. One is called FDG, a sugar that many living cells need for energy. The second is called [18F] dihydro-testosterone (DHT), which targets a protein called an “androgen receptor” that is present in particularly high levels in prostate cancer cells. Patients will receive either one or both of these radiotracers.
The primary purpose of this study is to learn how accurately DHT identifies areas of active prostate cancer, compared to standard imaging tests such as bone scans, CT, and MRI. The areas of possible cancer seen on the PET scan will be compared to those areas observed on CT, MRI, and bone scans.