Multiple primary malignant tumors of upper gastrointestinal tract: a novel role of 18F-FDG PET/CT.

AIM: To evaluate the capacity of (18)F-fluorodeoxyglucose positron emission tomography/computed tomography ((18)F-FDG PET/CT) for detecting multiple primary cancer of upper gastrointestinal (UGI) tract.

METHODS: Fifteen patients (12 without cancer histories and 3 with histories of upper GI tract cancer) were investigated due to the suspicion of primary cancer of UGI tract on X-ray barium meal and CT scan. Subsequent whole body (18)F-FDG PET/CT scan was carried out for initial staging or restaging. All the patients were finally confirmed by endoscopic biopsy or surgery. The detection rate of multiple primary malignant cancers was calculated based on (18)F-FDG PET/CT and endoscopic examinations.

RESULTS: (18)F-FDG PET/CT scan was positive in 32 suspicious lesions, 30/32 were true positive primary lesions, and 2/32 were false positive. In 15 suspicious lesions with negative (18)F-FDG PET/CT scan, 12/15 were true negative and 3/15 were false negative. Among the 15 patients, 12 patients had 29 primary synchronous tumors confirmed by pathology, including 8 cases of esophageal cancers accompanied with gastric cancer and 4 of hypopharynx cancers with esophageal cancer. The other 3 patients had 4 new primary metachronous tumors, which were multiple primary esophageal cancers. PET/CT imaging detected local lymph node metastases in 11 patients. Both local lymph node metastases and distant metastases were detected in 4 patients. On a per-primary lesion basis, the sensitivity, specificity, accuracy, negative predictive value and positive predictive value of (18)F-FDG PET/CT for detecting multiple primary cancer of UGI tract were 90.9%, 85.7%, 89.4%, 80% and 93.7%, respectively.

CONCLUSION: The whole body (18)F-FDG PET/CT may play an important role in evaluating the multiple primary malignant tumors of UGI tract cancer.