Limitation of PET/CT for Screening of Synchronous Upper Gastrointestinal Cancer in Oral Cancer Patients

Objective: Patients with squamous cell carcinoma (SCC) of the head and neck including the oral cavity have a high risk of upper gastrointestinal cancer, especially esophageal cancer. Synchronous upper gastrointestinal cancers affect the field of radiation or surgery, and undetected double cancer can cause poor prognosis. The purpose of this retrospective study was to evaluate the diagnostic performance of 18 F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) for detecting synchronous upper gastrointestinal cancer at the initial staging of oral cancer patients.Methods: Between September 2006 and August 2021, 804 newly diagnosed oral squamous cell carcinoma patients who undergo esophagogastroduodenoscopy (EGD) and FDG-PET/CT at the initial staging were enrolled in this study. The incidence of synchronous upper gastrointestinal cancer in EGD screening at the initial staging of oral cancer was retrospectively calculated. Furthermore, we evaluated the diagnostic performance of FDG-PET/ CT for screening of synchronous upper gastrointestinal cancer in oral cancer patients. Results: The incidence of synchronous upper gastrointestinal cancer in EGD screening at the initial staging of oral cancer was 4.2% (34/804 patients). Of 34 oral cancer patients with synchronous upper gastrointestinal cancer, 26 (76.5%) had both smoking and drinking habits. The sensitivity, specificity, accuracy, false-negative rate, falsepositive rate, positive predictive value, and negative predictive value of FDG-PET/CT for synchronous upper gastrointestinal cancer were 44.1%, 99.6%, 97.3%, 55.9%, 0.4%, 83.3%, and 97.6%, respectively.Conclusions: Because PET/CT cannot sufficiently detect synchronous upper gastrointestinal cancer in oral SCC patients, EGD screening before the treatment may be suitable for the high-risk oral SCC patients.