Eilber and his team of top scientists, including PET scan inventor Michael Phelps, wanted to find a better way to predict response so patients would not have to undergo unnecessary treatment or be removed from therapies that were working. Since operable sarcomas are treated before surgery with chemotherapy and radiation, it was the ideal cancer in which to compare PET scanning to CT.
CT and MRI scans provide anatomical pictures of the body, while PET images many different biochemical functions in real time, acting as a sort of molecular camera. Unlike CT and MRI, PET doesnt just take a snapshot of body structures, it watches what the body is doing.
In this study, researchers measured the metabolic activity of the tumor, or how much sugar was being consumed in the cancer cells. Cancer cells, because theyre growing uncontrollably, use much more sugar than do normal cells. Using a specific PET probe that measures sugar metabolism, researchers could determine whether the cancer cells in the tumor were still alive and dividing after chemotherapy and radiation, Eilber said.
Researchers used a PET/CT scanner in the study, a technologic advance that combines the imaging modalities in one machine. The combined scanner allowed researchers to directly compare the before and after treatment scans for both tumor size and metabolic activity.
PET was much more sensitive in picking up response than size-based RECIST, Eilber said. RECIST missed a large percentage of patients that actually had a response. PET picked up all of the responders.
The study also has important implications for long-term patient follow-up, Eilber said. PET scanning quickly tells doctors how much of the tumor is dead. The amount of tumor that dies during treatment correlates with patient outcomes. If a large amount of the tumor is killed during treatment, sarcoma patients experience increased survival and lower recurrence rates.<
|Contact: Kim Irwin|
University of California - Los Angeles