Prognostic significance of the harmonized maximum standardized uptake value of 18F-FDG- PET/CT in patients with resectable oral tongue squamous cell carcinoma: a multicenter study

Objectives: To investigate the usefulness of harmonized 18F-FDG-PET/CT parameters for predicting the postoperative recurrence and prognosis of oral tongue squamous cell carcinoma (OTSCC)Methods: We retrospectively analyzed the cases of 107 OTSCC patients who underwent surgical resection at four institutions in Japan in 2010-2016 and evaluated the harmonized PET parameters of the maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) for the primary tumor as the pSUVmax, pMTV, and pTLG. For lymph node metastasis, we used harmonized PET parameters of nodal- SUVmax, nodal- total MTV (tMTV), and nodal- total TLG (tTLG). The associations between the harmonized PET parameters and the patients' relapse- free survival (RFS) and overall survival (OS) were evaluated by the Kaplan- Meier method and Cox proportional hazard regression analysis for model 1 (preoperative stage) and model 2 (preoperative + postoperative stages).Results: The harmonized SUVmax values were significantly lower than those before harmonization (p=0.012). The pSUVmax was revealed as a significant preoperative risk factor for RFS and OS. Nodal- SUVmax, nodal- tMTV, and nodal- tTLG were significant preoperative risk factors for OS. The combination of pSUVmax + nodal- SUVmax significantly stratified the patients into a low- risk group (pSUVmax <3.97 + nodal- SUVmax <2.85 or >= 2.85) and a high- risk group (pSUVmax >= 3.97 + nodal- SUVmax <2.85 or pSUVmax >= 3.97 + nodalSUVmax >= 2.85) for recurrence and prognosis (RFS: p=0.001; OS: p<0.001).Conclusions: The harmonized pSUVmax is a significant prognostic factor for the survival of OTSCC patients. The combination of pSUVmax and nodal- SUVmax identified OTSCC patients at high risk for recurrence and poor prognosis at the preoperative stage.