Impact of primary tumor volume and location on the prognosis of patients with locally recurrent nasopharyngeal carcinoma

Introduction:The properties of a tumor itself were considered the main factors determining the survival of patients with locally recurrent nasopharyngeal carcinoma(NPC)treated with intensity-modulated radiotherapy(IMRT).However,recurrent tumors were mainly evaluated by using the American Joint Committee on Cancer staging system,which was modeled on primary tumors and did not incorporate the tumor volume.This study aimed to investigate the prognostic values of the primary tumor location and tumor volume,and to determine whether evaluating these parameters could improve the current staging system.Methods:Magnetic resonance(MR)images for 229 patients with locally recurrent NPC who underwent IMRT were analyzed retrospectively.Results:The skull base,parapharyngeal space,and intracranial cavity were the most common sites of tumors.There was a difference in the survival between patients with T1 and T2 diseases(77.6%vs.50.0%,P<0.01)and those with T3 and T4 diseases(33.0%vs.18.0%,P=0.04)but no difference between patients with T2 and T3 diseases(50.0%vs.33.0%,P=0.18).Patients with a tumor volume≤38 cm3had a significantly higher survival rate compared with those with a tumor volume>38 cm3(48.7%vs.15.2%,P<0.01).Conclusions:A new staging system has been proposed,with T3 tumors being down-staged to T2 and with the tumor volume being incorporated into the staging,which may lead to an improved evaluation of these tumors.This new system can be used to guide the treatment strategy for different risk groups of recurrent NPC.