TEP au 18-FDG et cancers ORL : récidive et surveillance post-thérapeutique

Abstract

Recurrence of head and neck squamous cell carcinomas occurs early and currently, with poor prognosis. Post-therapeutic surveillance aims to diagnose a recurrence as early as possible in order to perform curative salvage therapy. The risk of recurrence is highest in locally advanced cancers. Morphological imaging, including Computed Tomography (CT Scan) and magnetic resonance imaging, can be limited by the anatomic changes following surgery and radiotherapy, and sometimes cannot provide early diagnosis of recurrence. Histology presents some risk of morbidity, especially in irradiated tissues, and sampling error. Positron Emission Tomography (PET) with 18F-fluorodeoxyglucose (FDG) is superior to conventional imaging for the diagnosis and staging of recurrence, especially when it is performed three months after the end of treatments. FDG-PET has high sensitivity and negative predictive value for recurrence, so that further morphological and invasive investigations should not be performed in case of negative examination. On the other hand, because of its limited specificity and positive predictive value, any positive PET finding should be documented, in order to avoid false positives findings. The diagnosis of recurrence is the field of application in which FDP-PET has the greatest impact on head and neck cancer management: it is considered as a standard. However, the interest of FDG-PET during systematic follow-up has not yet been confirmed. PET should only be performed in difficult cases and within evaluation protocols.