18F-FAMT-PET Is Useful for the Diagnosis of Lymph Node Metastasis in Operable Esophageal Squamous Cell Carcinoma
The role and potential usefulness of positron emission tomography (PET) scanning in certain tumors has been widely investigated in recent years. 18F-FAMT (L-[3-18F]-α-methyltyrosine) is an amino acid tracer for PET. This study investigated whether PET/CT with 18F-FAMT provides additional information for preoperative diagnostic workup of esophageal squamous cell carcinoma compared with that obtained by 18F-FDG (fluorodeoxyglucose) PET or CT.
PET/CT studies with 18F-FAMT and 18F-FDG were performed as a part of the preoperative workup in 21 patients with histologically confirmed esophageal squamous cell carcinoma.
For the detection of primary esophageal cancer, 18F-FAMT-PET exhibited a sensitivity of 76.2%, whereas the sensitivity for 18F-FDG-PET was 90.5% (P = 0.214). 18F-FAMT uptake in primary tumors showed significant correlation with depth of invasion (P = 0.005), lymph node metastasis (P = 0.045), stage (P = 0.031), and lymphatic invasion (P = 0.029). In the evaluation of individual lymph node groups, 18F-FAMT-PET exhibited 18.2% sensitivity, 100% specificity, 71.9% accuracy, 100% positive predictive value, and 70.0% negative predictive value, compared with 24.2%, 93.7%, 69.8%, 66.6%, and 70.2%, respectively, for 18F FDG-PET. CT exhibited 39.4% sensitivity, 85.7% specificity, 69.8% accuracy, 59.1% positive predictive value, and 73.0% negative predictive value. The specificity of 18F-FAMT-PET is significantly higher than that of 18F-FDG-PET (P = 0.042) and CT (P = 0.002). 18F-FAMT-PET did not have any false-positive findings compared to those with 18F-FDG-PET.
Our findings suggest that the addition of 18F-FAMT-PET to 18F-FDG-PET and CT would permit more precise staging of esophageal cancer.
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