Fluorine-18-α-methyltyrosine positron emission tomography for diagnosis and staging of lung cancer:: A clinicopathologic study

Purpose: L-[3-F-18]-alpha-Methyltyrosine ([F-18] FMT) is an amino acid tracer for positron emission tomography (PET). We evaluated the diagnostic usefulness of [F-18] FMT PET in non - small-cell lung cancer (NSCLC) patients. Tumor uptake of [F-18] FMT was compared with that of 2-[F-18]-fluoro-2-deOXy-D-glucose ([F-18] FDG) and correlated with L-type amino acid transporter 1 (LAT1) expression. Experimental Design: Fifty NSCLC patients were enrolled in this study, and a pair of PET study with [F-18] FMT and [F-18] FDG was done. LAT1 expression and Ki-67 labeling index of the resected tumors were analyzed by immunohistochemical staining. Results: For the primary tumor detection, [F-18] FMT PET exhibited a sensitivity of 90% whereas the sensitivity for [F-18] FDG PET was 94%. For lymph node staging, the sensitivity and specificity of [F-18] FMT PET were 57.8% and 100%, and those of [F-18] FDG PET were 65.7% and 91%, respectively. The expression of LAT1 in squamous cell carcinoma and large cell carcinoma was significantly higher than that in adenocarcinoma. [F-18] FMT uptake was also higher in squamous cell carcinoma and large cell carcinoma than in adenocarcinoma, Uptake of [F-18] FMT in the tumor is closely correlated with LAT1 expression (rho = 0.890). Conclusion: [F-18] FMT PET had no false-positives in the detection of primary tumor and lymph node metastasis and could improve the diagnostic performance in NSCLC. Uptake of [F-18] FMT correlated with the expression of LAT1 that showed a significant association with cellular proliferation.