NEW ORLEANS - PET imaging can detect metastases missed by CT and technetium bone scans in children with bone sarcomas, according to a presentation Thursday at the American Association of Orthopaedic Surgeons meeting.
Dr. Jeremy C. Johnson from the University of North Carolina, Carolinas Medical Center in Charlotte, said his group has been studying PET as a staging tool for both bone and soft-tissue sarcomas since 1994. In an earlier study of 44 adult patients, the use of PET was associated with the "clinical upstaging of 18% of patients."
Johnson and colleagues currently have 1,277 patients who were referred for PET evaluation as part of clinical staging. Thirty-five of them were pediatric sarcoma patients. "In this subset of patients, use of PET resulted in a change in clinical management in 11%," he said. The patients ranged in age from 6 to 29 years.
All 35 patients were referred for evaluation of suspected bone sarcomas. In addition to PET, the patients underwent standard evaluation, which included chest x-ray, chest CT, technetium bone scan, and MRI of the sarcoma site. The tumor-volume resolution on PET was 7-10 mm, compared to resolutions of 2-5 mm for CT and 2-5 mm for MRI.
PET detected metastases in 10 of 35 (29%) of these patients at initial staging. Seven of the ten (70%) were non-pulmonary metastases which were not detected by CT. "Additionally, six were bony (metastases) that were not detected by bone scan," Johnson said. "The advantage to PET is that it can study the whole body and detect occult, non-pulmonary lesions that are missed by standard staging protocols," Johnson said.
Dr. Francis Hornicek from Massachusetts General Hospital in Boston asked if PET could be used to track the response to chemotherapy or to evaluate sentinel nodes. Johnson said his group has not used PET to evaluate either chemotherapy response or for staging of lymph nodes.
Session attendee Dr. Martin Malawer, director of orthopedic oncology at the Washington Cancer Institute in Washington, DC, said his center is using PET to evaluate some sarcoma cases, "and we frequently pick up lymph nodes, suggesting utility for sentinel node (imaging) as well."
By Peggy PeckAuntMinnie.com contributing writer
February 7, 2003
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