Screening examinations for double cancer in patients with oral cancer: usefulness of gastrointestinal endoscopy and positron emission tomography

: Many patients with oral cancer have double cancers, especially in the upper gastrointestinal tract. We studied synchronous double cancers in 138 patients with oral cancer who underwent gastrointestinal endscopy and 161 who underwent positron emission tomography（PET）preoperatively. Fifteen patients（10.9 ％）had cancer or precancerous lesions in the upper gastrointestinal tract on gastrointestinal endoscopy: 10 in the esophagus and 5 in the stomach. The histopathological diagnosis was severe epithelial dysplasia in 6 patients, carcinoma insitu in 4, and carcinoma in 5. These 15 lesions were asymptomatic and detected by gastrointestinal endscopy for the first time. Patients with severe epithelial dysplasia were observed, and those with carcinoma or carcinoma insitu underwent radical therapy. All of these gastrointestinal lesions were treated successfully, without any recurrence or metastasis. Double cancers were detected by PET in 3 patients（1.9 ％）: lung and esophageal cancer, gastric cancer, and ovarian cancer in one patient each. These 3 cases also were detected by PET for the first time and were free of clinical symptoms. Radical therapy was performed in 2 patients. The other patient had advanced disease and received only palliative therapy. Although PET could not detect most cancers or precancerous lesions in the upper gastrointestinal tract that could be detected by gastrointestinal endscopy, it was useful for detecting malignant lesions in sites other than the upper gastrointestinal tract. Our results suggest that preoperative gastrointestinal endscopy and PET examinations can detect double cancer in the early stage and contribute to better outcomes in patients with oral cancer.