Primary tumor volume of nasopharyngeal carcinoma: prognostic significance for recurrence and survival rate

We conducted a retrospective study to evaluate the effect of primary tumor volume on treatment outcomes in patients with nasopharyngeal carcinoma (NPC) who were treated with radiotherapy (RT)/concurrent chemoradiotherapy (CCRT) or CCRT with adjuvant chemotherapy. A total of 106 patients with newly diagnosed NPC were enrolled in this study. Magnetic resonance imaging (MRI)-derived primary tumor volume [gross tumor volume of the primary and involved retropharyngeal nodes (GTV-P)] was calculated. All patients received a total dose of 70–75 Gy. Forty-three patients (40.6%) received CCRT and 28 patients (26.4%) received CCRT with adjuvant chemotherapy. The median of primary tumor volume was 13.8 ml. Using T stage as covariate, primary tumor volume remained an independent prognostic factor for distant metastasis [hazard ratio (HR) 1.036; P = 0.04), for any relapse (HR 1.03; P = 0.03) and overall survival (HR 1.08; P = 0.0001). In the large tumor volume group (GTV-P > 15 ml), the 3-year metastasis-free survival rate, with and without adjuvant chemotherapy, was 100 and 69.2%, respectively (P = 0.014). Their 3-year recurrence-free survival rate, with and without adjuvant chemotherapy, was 94.7 and 66.7%, respectively (P = 0.035). This phenomenon was not observed in NPC patients with small tumor volume (GTV-P ≤ 15 ml). Our findings suggested that the risk of recurrence in NPC patients with small tumor volume is low. NPC with large tumor volume is associated with more recurrence and poor survival rates. These high-risk patients should be the group to benefit from CCRT followed by adjuvant chemotherapy.