Forecasts Impact of the Pre-therapeutic TEP-TDM in the 18-FDG Restaging of Upper Aero-digestive Tract Cancers

Head and neck (HN) cancer is the sixth most common malignancy worldwide, with around 800 000 new cases and 320 000 deaths in 2015. These malignancies encompass cancers of the oral cavity, oropharynx, hypopharynx and larynx and concern squamous cell carcinomas (HNSCC) 90% of the time. Despite aggressive treatment strategies, the five-year survival rate has only marginally improved in the past decade. The prognosis is strongly dependent on initial staging. The 5-year relative survival rate is 80,3% for patients with localized disease whereas it decreases to 47.2% when regional lymph node metastasis is known, and to 32.5% when distant metastasis is known. Hence, precise cancer staging is essential as it allows clinicians to select the appropriate treatment strategies and predict the prognosis of the patients.

The conventional work-up (CWU) includes physical examination, endoscopy, computed tomography (CT) and/or magnetic resonance imaging (MRI) of the head and neck to evaluate the initial local and regional HNSCC staging. Thoracic CT is recommended because the thorax is the most frequent location of remote metastasis and synchronous second cancer outside of the upper aerodigestive tract.

Some authors demonstrated that 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) had a higher sensitivity and specificity for determining the extent of the disease and was able to detect occult second primaries. Moreover 18-FDG PET-CT allows whole body assessment. This is why the use of 18-FDG PET-CT has increased significantly over the last several years. Added to initial CWU, 18-FDG PET-CT may restage HNSCC and as a result may alter the clinical management.

Pre-therapeutic 18F-FDG PET/CT is recommended by guidelines to assess remote extension of locally advanced HNSCC and/or to look for synchronous cancer but is not systematically indicated, particularly for localized disease.

Restaging impact on prognosis and clinical management remains poorly understood.

Therefore, the objective of this study is to assess the impact of the additional information provided by 18F-FDG PET-CT on HNSCC initial staging and whether restaging modify prognosis and clinical management, whatever the CWU stage.