Fluorine-18 fluorodeoxyglucose positron emission tomography predicts lymph node metastasis, P-glycoprotein expression, and recurrence after resection in mass-forming intrahepatic cholangiocarcinoma

Background Patients with intrahepatic cholangiocarcinoma (ICC) have a poor prognosis, and lymph node metastasis is an important prognostic factor. In this study, we investigated the usefulness of fluorodeoxyglucose positron emission tomography (FDG-PET) as a marker for lymph node metastasis, P-glycoprotein (P-gp) expression, and recurrence in ICC. Methods The subjects were 35 patients who underwent FDG-PET. Detectability of lymph node metastasis using FDG-PET was compared with that using computed tomography (CT) or magnetic resonance imaging (MRI). In patients who underwent resection, expression of P-gp was examined immunohistochemically, and the relationship between P-gp expression and the standardized uptake value (SUV) in FDG-PET was investigated. Survival rates were analyzed using clinical and pathologic factors. Results Of the 35 patients, 5 did not undergo surgery based on FDG-PET findings (2 with extrahepatic metastasis, and 3 with para-aortic lymph node metastasis) and 3 underwent laparotomy only (2 with peritoneal dissemination and 1 with para-aortic lymph node metastasis). The diagnostic accuracies of FDG-PET, CT, and MRI for detection of lymph node metastasis were 86%, 68%, and 57%, the sensitivities were 43%, 43% and 43%, and the specificities were 100%, 76%, and 64%, respectively. A negative correlation was found between SUV and P-gp expression ( P = .002; r = −0.62). The disease-free survival rates in the high SUV group (≥8.5) were significantly lower than in the low SUV group (