F‐18‐fluoro‐deoxy‐glucose positron‐emission tomography scanning in detection of local recurrence after radiotherapy for laryngeal/ pharyngeal cancer

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Abstract
Background The objective of this investigation was to determine whether F18‐fluoro‐deoxy‐glucose (FDG) positron‐emission tomography (PET) could differentiate between local recurrence and late radiation effects after radiotherapy for laryngeal/pharyngeal cancer. Methods In a prospective study of 75 patients (67 larynx, eight oro/hypopharynx), 160 laryngoscopies and 109 FDG PET scans were performed on the head and neck region. The mean follow‐up time after the first FDG PET scan was 23 months (minimum 1 year). Results Local recurrence was diagnosed in 37 patients: 19 after the first biopsy and 18 after follow‐up biopsies. For all of the negative initial FDG scans (27), the biopsies that were taken at the same time were negative and no recurrence was seen for at least 1 year. The first FDG scan was a true positive in 34 of 48 patients. In 12 of the 14 patients with false‐positive results, FDG scans were repeated; a decreased FDG uptake was found in 9 of the 12. The sensitivity and specificity of the first scan were respectively 92% and 63%; including subsequent FDG scans, the rates were 97% and 82%, respectively. Conclusions When a local recurrence is suspected after radiotherapy for cancer of the larynx/pharynx, an FDG PET scan should be the first diagnostic step. No biopsy is needed if the scan is negative. If the scan is positive and the biopsy negative, a decreased FDG uptake measured in a follow‐up scan indicates that a local recurrence is unlikely. © 2001 John Wiley & Sons, Inc. Head Neck 23: 933–941, 2001.