An analysis of clinical and dosimetric factors for postradiation nasopharyngeal necrosis in intensity-modulated radiotherapy for nasopharyngeal carcinoma

Abstract

Objective To investigate the influencing factors for postradiation nasopharyngeal necrosis (PRNN) by analyzing clinical characteristics, prognosis, and dosimetry of PRNN after initial intensity-modulated radiotherapy (IMRT) for nasopharyngeal carcinoma (NPC). Methods A retrospective analysis was performed among 1217 patients with NPC who received initial IMRT from 2001 to 2013. Twenty-one patients were diagnosed with PRNN by clinical symptoms, endoscopy, magnetic resonance imaging, and pathological evidence (not including local recurrence). The clinical characteristics and prognosis were summarized and the radiotherapy plans were reassessed for dosimetric evaluation. Results In the 21 patients with PRNN, 17 were male and 4 female; one patient was in stage T2, 3 in stage T3, and 17 in stage T4. The median volume of gross tumor was 83 cm3. All patients received radiotherapy with a prescribed dose of 73.92 Gy except one patient with stage T2 disease who received a prescribed dose of 69.96 Gy. The time to PRNN after radiotherapy ranged between 1.8 and 21.9 months (median time=6.2 months). The incidence of massive nasopharyngeal bleeding was 48%(10/21). In the 21 patients, 6 recovered form PRNN, 15 remained ill, and 8 patients died, consisting of 4 who died of massive nasopharyngeal bleeding, 3 of cachexia with multiple organ failure, and 1 of multiple bone metastases. Conclusions PRNN is one of the severe adverse reactions after IMRT for NPC. The development of PRNN is related to advanced T stage, large tumor volume, poor nutritional status, infection, radiotherapy dose, and intense treatment. Massive nasopharyngeal bleeding and cachexia are the primary causes of death in patients with PRNN. Key words: Nasopharyngeal neoplasms/three-dimensional radiotherapy; Radiation nasopharyngeal necrosis; Factor analysis