Preliminary Results of Re-irradiation for Locally Recurrent Nasopharyngeal Carcinoma with Intensity Modulated Radiotherapy

Abstract

To evaluate the treatment outcome and radiation toxicity in patients with locally recurrent nasopharyngeal carcinoma (NPC) treated with intensity-modulated radiation therapy (IMRT). From Jun 2006 to January 2009,53 patients with locally recurrent NPC received re-irradiation using IMRT. The rT classification distribution was 13 for rT1,2 for rT2,16 for rT3 and 22 for rT4. N1 and N2 disease was found in 12 (8 for N1, 4 for N2) patients. The number of patients with Stage I, IIa-b, III, IVa disease was 9, 4, 18, and 22, respectively. Median time from initial radiotherapy to the nasopharyngeal recurrence was 55 months. All patients were treated with 6MV photon with 7-9 fields. The gross tumor volume (GTV) in the nasopharynx received a median prescription dose of 6720cGy (5846-7200cGy),with median fractionation of 2Gy (1.9-2.2Gy). Thirty-five patients received cisplatin-based induction or concurrent or adjuvant chemotherapy. Median follow-up time was 20 months (range, 2-47 months). Ninety-six percent of GTV received 95% of the prescribed dose (V95-GTV).The dose encompassing 95% of GTV (D95-GTV) was 67.9 Gy. The average dose covered of GTV was 66.7Gy. The doses of surrounding critical structures were lower than the tolerable thresholds. After re-irradiation, 74% patients had complete response of primary tumor. Twenty six percent of patients had partial response. One-year and 2-year overall survival and progression-free survival rates were 71.7%, 69.8% and 58.7%,52.3%,respectively. Up to the date of last following up (March 2010),22 patients died. Ten patients died of nasopharynx hemorrhage. Two patients developed recurrence in the nasopharynx and neck respectively. Acute toxicity was acceptable according to the Radiation Therapy Oncology Group criteria. Grade 3-4 toxicities were reported in 12 patients. Severe late complications such as eyeball damage/blindness and loss of hearing were observed in 5 patients. Our preliminary results showed that IMRT is feasible for patients with recurrent NPC. High dose IMRT may result in radio-necrosis of nasopharyngeal mucosa and bleeding. The hemorrhage was the main death cause. The incidence of serious toxicities was relatively low. More patients and longer term follow-up are warranted to evaluate late toxicities and treatment outcome.