New research at Wake Forest University Baptist Medical Center shows that Positron Emission Tomography (PET) is more accurate than conventional imaging in identifying patients who have good responses to chemotherapy and radiation treatment -- a finding that could one day help some patients avoid surgery.
The results, from a study of 64 patients with esophageal cancer, are published in the April issue of Annals of Surgery. PET, a technology that produces images of the metabolic function of tissue, was used to test patients for cancer after treatment with a combination of chemotherapy and radiation (chemoradiation).
"While additional multi-center studies are needed, the research clearly shows that PET is a useful tool for identifying patients who respond well to chemoradiation," said Edward A. Levine, M.D., lead investigator. "Being able to identify these responders may alter the need to take some patients to surgery."
Over the past two decades, the most common treatment for esophageal cancer has been chemoradiation followed by surgery. Even with these treatments, the prognosis is poor for most patients, with long-term control rates of 25 to 35 percent. Some patients, however, respond well to chemoradiation and have improved long-term survival.
Identifying which patients will respond to chemoradiation alone -- and perhaps avoid surgery to remove part of the esophagus -- has been difficult. Conventional imaging, including both computed tomography (CT) and endoscopic ultrasound (EUS), are poor predictors of response to chemoradiation.
Recently, PET was shown to be more accurate than CT and EUS in evaluating newly diagnosed patients to determine the extent of the disease. So, Wake Forest researchers decided to evaluate its ability to determine response to chemoradiation.
"The technology has allowed us to evaluate the varying responses to chemoradiation in a cross-section of patients," said Levine, professor of surgery and chief of the Section of Surgical Oncology. "We have identified a subgroup of patients with good long-term control rates and improved long-term survival."
The researchers conducted the study between 2000 and 2004 in patients whose cancer had not spread beyond the esophagus and lymph nodes. Patients had a PET scan both before and after chemoradiation. Then, four to six weeks later, eligible patients had surgery to remove part of the esophagus. The surgical pathology reports from 41 patients were compared to PET results -- and PET was found to be 88 percent accurate at correctly identifying patients without disease.
"These results show the predictive power of pre-treatment PET imaging for identifying patients likely to experience a significant tumor response following a course of pre-operative chemoradiation," said Levine. "The evidence suggests the potential for PET to change clinical practice, perhaps helping some patients avoid surgery."
This study was supported, in part, by a grant from the National Cancer Institute.
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