Prognostic Value of Volume-Based -Fluorodeoxyglucose PET/CT Parameters in Patients with Clinically Node-Negative Oral Tongue Squamous Cell Carcinoma

Objective: To evaluate the prognostic value of volume-based metabolic parameters measured with $^{18}F$-fluorodeoxyglucose ($^{18}F$-FDG) positron emission tomography (PET) in patients with clinically node-negative (cN0) oral tongue squamous cell carcinoma (OTSCC) as compared with other prognostic factors. Materials and Methods: In this study, we included a total of 57 patients who had been diagnosed with cN0 tongue cancer by radiologic, $^{18}F$-FDG PET/CT, and physical examinations. The maximum standardized uptake value ($SUV_{max}$), average SUV ($SUV_{avg}$), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) for primary tumors were measured with $^{18}F$-FDG PET. The prognostic significances of these parameters and other clinical variables were assessed by Cox proportional hazards regression analysis. Results: In the univariate analysis, pathological node (pN) stage, American Joint Committee on Cancer (AJCC) stage, $SUV_{max}$, $SUV_{avg}$, MTV, and TLG were significant predictors for survival. On a multivariate analysis, pN stage (hazard ratio = 10.555, p = 0.049), AJCC stage (hazard ratio = 13.220, p = 0.045), and MTV (hazard ratio = 2.698, p = 0.033) were significant prognostic factors in cN0 OTSCC patients. The patients with MTV ${\geq}$ $7.78cm^{3}$ showed a worse prognosis than those with MTV < $7.78cm^{3}$ (p = 0.037). Conclusion: The MTV of primary tumor as a volumetric parameter of $^{18}F$-FDG PET, in addition to pN stage and AJCC stage, is an independent prognostic factor for survival in cN0 OTSCC.