Prediction of Pathologic Grade and Prognosis in Mucoepidermoid Carcinoma of the Lung Using ¹⁸F-FDG PET/CT

The maximum standardized uptake value (SUVmax) of pulmonary mucoepidermoid carcinoma (PMEC) in fluorine-18fluorodeoxyglucose positron emission tomography/computed tomography ((18)F-FDG PET/CT) was evaluated as a preoperative predictor of pathologic grade and survival rate. Twenty-three patients who underwent preoperative PET/CT and complete resection for PMEC were enrolled. The optimal cut-off SUVmax for tumor grade was calculated as 6.5 by receiver operating characteristic curve. The patients were divided into a high SUV group (n = 7) and a low SUV group (n = 16). Clinicopathologic features were compared between the groups by χ(2) test and overall survival was determined by Kaplan-Meier analysis. The mean SUVmax was 15.4 ± 11.5 in the high SUV group and 3.9 ± 1.3 in the low SUV group. All patients except one from the low SUV group had low grade tumors and all had no nodal metastasis. The sensitivity and specificity of SUVmax from PET/CT for predicting tumor grade was 85.7% and 93.8%, respectively. During the follow-up period (mean, 48.6 ± 38.7 months), four patients from the high SUV group experienced cancer recurrence, and one died of cancer. In contrast, none of the low SUV group had recurrence or mortality. Five-year overall survival rate was significantly higher in the low SUV group (100% vs. 71.4%, p = 0.031). Pulmonary mucoepidermoid carcinoma patients with high SUVmax in PET/CT had higher tumor grade, more frequent lymph node metastasis and worse long-term outcome. Therefore, PMEC patients with high uptake on PET/CT imaging might require aggressive mediastinal lymph node dissection and adjuvant therapies.