Limitation of 2-deoxy-2-[F-18]fluoro-D-glucose positron emission tomography (FDG-PET) to detect early synchronous primary cancers in patients with untreated head and neck squamous cell cancer

Patients with head and neck squamous cell carcinoma (HNSCC) often develop synchronous multiple primary cancers. It is important to detect second primary cancer in HNSCC patients, because it influences treatment selection of primary cancer. The aim of this study was to evaluate the utility of 2-deoxy-2-[F-18]fluoro-d-glucose (FDG)-positron emission tomography (PET) for detecting synchronous primary cancers at the initial staging of patients with HNSCC. Three hundred and forty-seven patients with untreated HNSCC underwent FDG-PET with or without computed tomography fusion and other routine workups, including upper gastrointestinal Lugol chromoendoscopy, for the initial staging. We examined the prevalence of second primary cancer in these patients and the utility of PET. We identified 57 synchronous primary cancers in 53 patients, of which only 33 % were detected with PET. The most common site for the second primary cancer was the esophagus (49 %), followed by stomach (14 %) and head and neck (11 %). Most early-stage esophageal cancers and stomach cancers were detected using Lugol chromoendoscopy but not PET. Although PET is useful for detecting synchronous primary cancers, it is not a sensitive technique for detecting early esophageal cancers and gastric cancers. Therefore, Lugol chromoendoscopy is indispensable for detecting synchronous upper gastrointestinal cancers in HNSCC patients.