• Yu-Hung Chen, Kai-Ping Chang, Sung-Chao Chu, Tzu-Chen Yen, Ling-Yi Wang, Joseph Tung-Chieh Chang, Cheng-Lung Hsu, Shu-Hang Ng, Shu-Hsin Liu, and Sheng-Chieh Chan.
• Department of Nuclear Medicine, Hualien Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, Hualien, Taiwan.
• Eur. J. Nucl. Med. Mol. Imaging. 2019 Mar 1; 46 (3): 650-660.

PurposeTo determine the value of early evaluation of response to concurrent chemoradiotherapy (CCRT) using 18F-FDG PET-derived parameters and the Epstein-Barr virus (EBV) DNA titre in outcome prediction in patients with primary nasopharyngeal carcinoma (NPC).MethodsSixty patients with primary NPC were prospectively enrolled. All patients underwent 18F-FDG PET/CT before and during CCRT. The plasma EBV DNA titre was measured along with the PET/CT-derived parameters. Changes in EBV DNA titre and PET/CT-derived parameters during CCRT were analysed in relation to response to treatment, recurrence-free survival (RFS) and overall survival (OS).ResultsA total lesion glycolysis (TLG) reduction ratio of ≤0.6 and a detectable EBV DNA titre during CCRT were predictors of an unfavourable response to treatment, RFS and OS. In multivariate analysis, a TLG reduction ratio of ≤0.6 predicted incomplete remission (p = 0.002) and decreased RFS (p = 0.003). The proportion of patients with a TLG reduction ratio of >0.6 who achieved a complete response was more than twice that of patients with a TLG reduction ratio of ≤0.6. A detectable EBV DNA titre, a TLG reduction ratio of ≤0.6 and older age were independently associated with a poorer OS (p = 0.037, 0.009 and 0.016, respectively). A scoring system was developed based on these independent predictors of OS. Patients with a score of 1 and 2/3 had poorer survival outcomes than those with a score of 0 (hazard ratio 4.756, p = 0.074, and hazard ratio 18.973, p = 0.001, respectively). This scoring system appeared to be superior to the traditional TNM staging system (p < 0.001 versus p = 0.175).ConclusionEarly evaluation of response to CCRT using 18F-FDG PET-derived parameters and the EBV DNA titre can predict outcome in patients with primary NPC. A combination of interim PET parameters and the EBV DNA titre enables better stratification of patients into subgroups with different survival rates.

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