This is a prospective study aiming to evaluate the predictive value of 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET/CT), reflected in terms of disease-free survival (DFS) and overall survival (OS), in pediatric patients who had received post induction chemotherapy for locally advanced nasopharyngeal carcinoma (LANPC). Pediatric patients were treated definitively with 3 courses of induction platinum-based chemotherapy followed by concurrent chemoradiation (CRT) with simultaneous integrated boost intensity-modulated radiotherapy (SIB-IMRT) .
This is a prospective study included LANPC (stage II-III) pediatric patients treated definitively and consecutively between January 2008 and December 2014 with induction chemotherapy; cisplatin, and 5-fluorouracil (PF) followed by SIB-IMRT to a total dose 61.2Gy with utilizing weekly cisplatin. The volume of radiotherapy was based on tumor response to Induction chemotherapy. All patients had baseline pretreatment and post induction chemotherapy 18F-FDG PET/CT. Metabolic response of the primary tumor and LN was assessed using maximum standardized uptake value (SUVmax) that was correlated with treatment outcomes; OS and EFS.
The study included 38 eligible pediatric LANPC patients. The 3-year OS and DFS rates were 84.6 % and 79.5%, respectively. The median OS and EFS intervals were not reached. On a univariate analysis, the 3-years OS and EFS were significantly higher in patients with post induction metabolic regression of SUV max >65% for the primary and 57% for the nodal metastases (P = 0.02). Furthermore, OS and EFS were lower in patients with initial high nodal metabolic activity (P = 0.004) and (P = 0.005) with SUV max cutoff values (14.5) and (6.9) respectively. Also Initial SUV-LN > SUV-Primary showed significant lower OS (P = 0.004) and EFS (P = 0.005).
In this study, the degree of metabolic regression in post-induction chemotherapy 18F-FDG PET/CT was a potential independent prognostic indicator for clinical outcomes in LANC pediatric patients (treated definitively with PF induction chemotherapy followed by CRT). Further controlled clinical trials are worthwhile.
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All authors have declared no conflicts of interest.