Clinical usefulness of F-18 FDG PET in lymphoepithelioma-like gastric carcinoma

- F-18 FDG PET/CT showed high sensitivity for AGC in gastric LELC.
- F-18 FDG PET/CT showed high specificity for lymph node metastasis and distant metastasis in gastric LELC.
- F-18 FDG PET/CT detected or excluded recurrence with high accuracy, particularly in cases with discrepancies between abdominal CT findings and tumor marker levels during follow-up.

PurposeLymphoepithelioma-like carcinoma (LELC) is a rare type of gastric cancer. We evaluated the clinical usefulness of F-18 FDG positron emission tomography/computed tomography (PET/CT) in LELC of stomach.Materials and methodsA total of 28 patients (mean age = 59 years) who underwent preoperative F-18 FDG PET/CT were enrolled retrospectively. Nine patients underwent follow-up F-18 FDG PET/CT. Pathologic information was obtained through gastrectomy and the association with Epstein-Barr virus (EBV) was investigated in 26 patients.ResultsPET/CT detected 85.0% (17/20) of advanced gastric cancers (AGC) and 12.5% (1/8) of early gastric cancers (EGC). Most tumors (23/26, 88.5%) were EBV-associated. The maximum standardized uptake value of FDG-avid tumors was 7.5 ± 3.0. The sensitivity and specificity of PET/CT for the presence of lymph node metastasis was 47.8% (11/23) and 100.0% (13/13), respectively. PET/CT also detected a hepatic sarcomatoid carcinoma in one patient. The specificity of PET/CT for distant metastasis or second malignancy was 96.3%. Follow-up PET/CT detected malignant lesions in 3 of 9 patients; a liver metastasis, recurrent hepatic sarcomatoid carcinomas and a metachronous cholangiocarcinoma. PET/CT correctly excluded recurrence in the rest of the patients (6/6). The sensitivity and specificity of PET/CT for detecting recurrence or second malignancy was 100% and 100%, respectively.ConclusionF-18 FDG PET/CT would be a useful tool in evaluating distant metastasis or recurrence in patients with gastric LELC.