New type of PET scan same as MRI, CT for false positives, study found
TUESDAY, May 13 (HealthDay News) -- An advanced imaging technique to detect head and neck cancer may not boost a patient's odds of receiving an early or more accurate diagnosis of the disease, new findings suggest.
Positron emission tomography with a radioactive tracer (18F-FDG PET) is one of three imaging techniques commonly used to check whether head and neck squamous cell cancer has spread to the nearby lymph nodes in such patients. This is important in determining the prognosis of the disease, since some patients who clinically appear free of these types of metastases may actually have small tumors within their lymph nodes.
The findings are based on an analysis of 32 previously published studies done on head and neck cancer patients with one or fewer nodal metastases. The team from the University of Ioannina School of Medicine, in Greece, found that FDG-PET failed to identify half the lesions in patients whose lymph nodes tested negative.
The analysis, published online May 13 in the Journal of the National Cancer Institute, also found that the imaging technique incorrectly identified normal tissue as being cancerous 13 percent of the time.
The sensitivity and accuracy of FDG-PET compared with the two other common imaging techniques used -- magnetic resonance imaging (MRI) and computed tomography (CT) -- appears to be slightly better, but researchers said the differences were not statistically significant. The rate of false positives for each of the three imaging techniques was similar.
"Thus, there is little evidence to support the routine use of 18F-FDG-PET to evaluate possible lymph node metastasis among patients with [head and neck squamous cell cancer] and a clinically negative neck," the authors wrote.
An accompanying editorial in the journal notes that clinicians typically use multiple imaging techniques and clinical examinations rather than a single test to compose a full picture of their patients condition and disease.
"Prospective data remain a critical necessity to translate imaging improvements with FDG-PET into proven treatment improvements," the editorialists wrote.
The U.S. National Cancer Institute has more about head and neck cancers.
-- Kevin McKeever
SOURCE: Journal of the National Cancer Institute, news release, May 13, 2008
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