Pretreatment FDG PET in prognosis of locoregionally advanced nasopharyngeal carcinoma treated with intensity-modulated radiation therapy

<b>Objectives:</b> We aimed to investigate the long-term survival benefit of PET/CT compared with the routine examination (chest CT, abdominal enhanced CT and emission computed tomography (ECT)) for locally advanced nasopharyngeal carcinoma (NPC) before treatment. <b>Methods:</b> From June 8^th 2005 to August 10^th 2017, 507 histologically diagnosed NPC patients with the 8th AJCC/UICC staging criteria III-IVA were enrolled in this study. Among them, patients underwent chest CT, abdominal enhanced CT and bone emission CT (control group), or replaced by positron emission tomography-CT (PET-CT group) to check for distant metastases. <b>Results:</b> The numbers of patients in the control and PET-CT group were 344 (67.9%) and 163 (32.1%), respectively. With the median follow-up of 72 months, a total of 127 (25.0%) patients died. The 5-year and 8-year overall survival (OS) rates of the control and PET-CT group were 81.1% and 86.9%, 70.8% and 74.6% (P=0.087), respectively. Patients with T1-3, III stage and TPF showed improved 5-year and 8-year OS rates compared with T4, IVA stage and PF patients (P=0.001, P=0.000 and P=0.009). Patients with initially PET-CT-based staged showed improved 5-year and 8-year distant control (DC) compared with the control group (90.6% vs. 83.3% and 90.6% vs. 81.0%, P=0.013). There was no significant difference in local control (LC) and regional control (RC), between the control and PET-CT group. <b>Conclusions:</b> Patients with initially PET-CT-based staged showed improved long-term DC compared with the control group. Initially PET-CT-based staged is recommended routinely in locoregionally advanced NPC.