The role of pretreatment FDG standard uptake value in predicting for clinical outcome in locally advanced nasopharyngeal carcinoma

Abstract

Objective To explore the prognostic value of pretreated maximum standardized uptake value (SUVmax) using 18-fluorodeoxyglucose positron emission tomography with computed tomography (18FDG PET/CT) in locally-advanced nasopharyngeal carcinoma (NPC) treated by intensity-modulated radiotherapy (IMRT).Methods One hundred and forty previously untreated stage Ⅲ - Ⅳb ( UICC/AJCC 6th) patients with biopsy-proven nasopharyngeal carcinoma were examined.All of the enrolled patients accepted whole body/head-neck 18FDG PET/CT before radical IMRT. 18FDG uptakes were recorded as SUVmax of primary tumor (SUVmax-P) and SUVmax of cervical lymph nodes (SUVmax-N).The relationships between SUVmax and long-term clinical outcomes were analyzed.Results The median SUVmax-P was 10.4,and the median SUVmax-N was 6.2.The SUVmax-P was weakly correlated with T-stage ( R =0.279,P =0.001 ).The SUVmax-N was weakly correlated with N stage ( R =0.334,P =0.000 ).There were no difference of the median SUVmax-P (9.2 vs.10.4,U =560.50,P =0.805 ) and the median SUVmax-N (4.0vs.5.0,U =576.00,P =0.908) between patients with and without local recurrence.The median SUVmax-P of patients with distant metastasis was significantly higher than those without metastasis (11.9 vs.9.8,U =987.50,P =0.014).The SUV of 10.2 was taken as a cut-off for high and low uptake tumors.For patients with SUVmax-P ＞ 10.2,the 5-year distant metastasis-free survival (DMFS) and 5-year overall survival (OS)were significantly higher than those with SUVmax-P ≤ 10.2 (69.1％ vs.95.5％,x2 =15.88,P =0.000;68.4％ vs.94.0％,x2 =15.56,P =0.000,respectively).Multivariate analysis showed that SUVmax-P was the only independent risk factor of 5-year DMFS and OS ( HR =7.87,P =0.001 and HR =5.14,P =0.003). Conclusion SUVmax-P is a useful biomarker predicting long-term clinical outcomes in newly diagnosed locally-advanced NPC patients. Key words: Nasopharyngeal neoplasms/intensity-modulated radiotherapy; Prognosis; Fluorodeoxyglucose maximum standard uptake value; Prediction value