Early PET Response to Chemo Predicts Survival in Sarcoma Patients

An early positron emission tomography (PET) response after the initial cycle of neoadjuvant chemotherapy can be used to predict increased survival in patients with soft tissue sarcomas.

Earlier research by a multidisciplinary team of physician scientists from the University of California, Los Angeles (UCLA) Jonsson Cancer Center (USA) had demonstrated that use of fluorodeoxyglucose (FDG) PET/computed tomography (CT) could determine pathologic response after the first dose of chemotherapy drugs. The researchers then wondered if the patients showing a significant PET response after the first round of chemotherapy also were surviving longer, according to Dr. Fritz Eilber, an associate professor of surgical oncology, director of the sarcoma program at UCLA’s Jonsson Cancer Center and senior author of the study.

“We did find that patients who experienced an early PET response to treatment had significantly increased survival,” Dr. Eilber said. “This is vital because patients want to know if the drugs are working and what that says about their ultimate outcome.”

The study was published April 1, 2012, in Clinical Cancer Research, a journal of the American Association of Cancer Research. In the study, 39 patients with soft tissue sarcoma underwent a PET scan to measure glucose uptake prior to getting chemotherapy. The patients underwent another PET scan after the first round of chemotherapy. Those whose tumors demonstrated a 25% or more decrease in metabolic activity--a response considered significant--were determined later to have significant increased survival rates compared to those patients who had less than a 25% decrease, according to Dr. Eilber. “It’s an important finding because we can now identify whether patients are getting the right chemotherapy very quickly,” he said. “Patients don’t want to have to wait until the cancer recurs or they die to find out whether their chemotherapy worked or not.”

Next, Dr. Eilber and his team are working to design new molecular imaging tools that may tell them even more about a patient’s cancer beyond the conventional FDG probe. “Just looking at the size of the tumor is not good enough anymore,” Dr. Eilber said. “We want to image what’s happening within the tumor in real time.”

The study was funded by the In vivo Cellular and Molecular Imaging Center at UCLA’s Jonsson Comprehensive Cancer Center and the US Department of Energy. “This study suggests that PET allows survival predictions after the initial cycle of neoadjuvant chemotherapy and might therefore potentially serve as an early endpoint biomarker,” the authors wrote in their article. “Such information cannot be derived from CT scanning based on serial tumor size measurements. The ability to assess treatment response early during the course of therapy can potentially guide management decisions. Treatment could be switched from neoadjuvant chemotherapy to immediate surgery in nonresponding patients, while it would be continued in responders. Such risk adapted therapy could reduce treatment associated morbidity and costs.”

Related Links:
University of California, Los Angeles’ Jonsson Cancer Center