Definitive intensity-modulated radiation therapy for nasopharyngeal carcinoma: long-term outcome of a multicenter prospective study.

PURPOSE

To evaluate long-term outcome in nasopharyngeal carcinoma (NPC) treated with intensity-modulated radiation therapy.

METHODS

Between January 2006 and August 2008, 300 patients with histologically proven NPC were enrolled in this multicenter prospective study. All patients received definitive IMRT. Cisplatin-based concurrent chemotherapy was given to patients with stages III-IVb disease.

RESULTS

Median follow-up time was 47.1 months (range 11-68 months). Median survival time was not reached. For all patients, the 4-year local control (LC), regional control (RC), distant metastasis-free survival (DMFS), and overall survival (OS) were 94.0, 95.1, 85.0, and 86.1 %, respectively. Thirty-five patients experienced locoregional failures: 18 were local only, 15 were regional only, and 2 were both local and regional. Forty-two patients developed distant metastasis. Of these, 32 patients had single organ metastasis, and 10 patients had multiple organ metastasis. The most common acute toxicities were mucositis, dermatitis, and xerostomia. Grade 0-2 mucositis, dermatitis, and xerostomia occurred in 200 patients (66.7 %), 288 patients (96.0 %), and 286 patients (95.3 %), respectively. Grade 3 mucositis, dermatitis, and xerostomia were seen in 100 patients (33.3 %), 12 patients (4.0 %), and 14 patients (4.7 %), respectively. No Grade 4 acute toxicities were observed. The most common late toxicity for 284 patients who survived for more than 2 years was xerostomia. At 3 months after treatment, 16.2 % of patients had Grade 1, 73.6 % had Grade 2, and 10.2 % had Grade 3 xerostomia. However, the severity of xerostomia decreased over time. At 24 months, only 12.3 % of patients had Grade 2 xerostomia, and none had Grade 3 or 4 xerostomia.

CONCLUSIONS

IMRT for NPC patients achieved excellent long-term locoregional control (LRC) and OS, with acceptable acute and late toxicities. After the treatment, xerostomia was improved over time. Distant metastasis remained the main cause of failure. More effective systemic therapy is demanding for reducing the risk of distant metastasis.