Limitations of FDG-PET and FDG-PET With Computed Tomography for Detecting Synchronous Cancer in Pharyngeal Cancer

Objective: To analyze the ability of fluorine-18 fluorodeoxyglucose positron emission tomography (FDGPET) and the fusion of FDG-PET with computed tomography (FDG-PET/CT) to detect synchronous upper gastrointestinal tract (UGI) cancer in newly diagnosed pharyngeal squamous cell carcinoma (SCC). Synchronous UGI cancer is a significant problem in treating pharyngeal SCC, particularly for Japanese populations reported to be at high risk. Good results have been reported from the use of FDG-PET and FDG-PET/CT in staging head and neck SCC ( HNSCC). An additional advantage is that both techniques are expected to prove useful in detecting synchronous cancer. Design: Retrospective analysis of medical records. Setting: Aichi Cancer Center, Nagoya, Japan. Patients: Forty-three Japanese patients with pharyngeal SCC were assessed for the ability of FDG-PET and FDG-PET/CT to detect synchronous UGI cancer via a comparison with UGI Lugol chromoendoscopy. The patients had undergone 17 FDG-PET and 26 FDG-PET/ CT scans before treatment. Main Outcome Measure: Sensitivity of FDG-PET and FDG-PET/CT to detect synchronous UGI cancer. Results: Pathologically, 6 patients with esophageal SCC (14%) and 4 with stomach adenocarcinoma (9%) were diagnosed on the basis of suspect lesions detected by UGI Lugol chromoendoscopy. One patient was found to have stage T2 esophageal cancer by FDG-PET/CT, but no patients had UGI cancer. The sensitivity of detecting T1 UGI cancer by FDG-PET and FDG-PET/CT was 0%. Conclusions: The choice of diagnostic technique must be based on the site and histologic characteristics of the synchronous tumor. Although FDG-PET and FDG-PET/CT are still the preferred techniques for staging HNSCC, neither replaces Lugol chromoendoscopy for detecting synchronous UGI cancer in high-risk populations.