(18)F-FDG and (18)F-FAMT PET-derived metabolic parameters predict outcome of oral squamous cell carcinoma

OBJECTIVES: L-3-[(18)F]-Fluoro-α-methyl tyrosine (FAMT), an amino acid positron emission tomography (PET) tracer, complements [(18)F]-fluorodeoxyglucose (FDG) in the diagnosis of malignancies. We compared the predictive ability of FAMT PET versus FDG PET regarding metastatic oral squamous cell carcinoma (OSCC) outcomes for distant metastasis, including lymph node metastasis, and identified the relevant metabolic parameters for each. METHODS: We enrolled 160 patients with OSCC who underwent PET/computed tomography using FDG and FAMT before treatment. Outcomes were assessed using clinicopathological characteristics such as the standardized uptake value (SUV(max), SUV(peak)), metabolic tumor volume (MTV), and total lesion glycolysis or total lesion retention. Univariate and multivariate Cox proportional hazards models were used to identify the independent predictors of disease-free survival (DFS) and overall survival (OS) during an average follow-up time of 1401.7 and 1646.0 days, respectively. Areas under the receiver operating characteristic curves were analyzed for the accuracy and predictive value of imaging parameters. RESULTS: Clinical parameters (excluding age) and PET metabolic parameters were significantly associated with OS. Multivariate analysis showed that an infiltrative growth pattern [p = 0.034, hazard ratio (HR) = 2.30], and the FDG-measured SUV(peak) (p = 0.045, HR = 2.45) were independent risk factors for DFS and that lymph node metastasis (p = 0.03, HR = 2.57) and the FAMT-measured MTV (p = 0.004, HR = 3.65) were independent risk factors for OS. CONCLUSIONS: In patients with OSCC, FDG PET predicted DFS, whereas FAMT predicted OS. The two PET tracers, combined with clinical parameters, provide complementary, outcome-related diagnostic information in OSCC.