Can 18F-FDG PET/CT Reliably Assess Response to Primary Treatment of Head and Neck Cancer?

Introduction: Where chemoradiotherapy or radiotherapy alone with curative intent is used as the primary treatment of locally advanced head and neck cancers, salvage surgery may offer a second chance of cure in the face of recurrent or residual disease. Early detection of recurrent or residual disease is therefore the key to facilitating timely and efficacious salvage surgery. CT and MRI can be difficult to interpret in the posttreatment neck. Functional imaging, such as F-18-FDG PET/CT, has the potential to improve restaging accuracy. The aim of our study was to assess the efficacy of F-18-FDG PET/CT performed 3 months following primary treatment of head and neck cancer.

Methods: We retrospectively reviewed 35 patients with head and neck squamous cell cancer (mean age, 61 years; 28 male patients) who underwent F-18-FDG PET/CT imaging at 3 months following primary treatment, which included chemoradiotherapy (n = 31) or radiotherapy alone (n = 4). Patient follow-up was available for at least 12 months (range, 12-48 months; median, 36 months). Scans were categorized as true positive, true negative, false positive, and false negative based on clinicoradiological follow-up and histology.

Results: Twenty patients had negative scans with no recurrence during the follow-up period, and 3 had false-negative scans with recurrent disease at 5, 8, and 12 months. Eleven patients had true-positive scans, confirmed histologically in all, and there was 1 false-positive scan giving a sensitivity of 79%, specificity of 96%, positive predictive value of 92%, negative predictive value of 87%, and overall accuracy of 89%.

Conclusions: F-18-FDG PET/CT is an accurate method for assessing response after primary locally advanced head and neck cancer treatment. Although false-positive scans are rare, a few patients will have a relapse after a negative scan, and so continued close follow-up is required.