Re-irradiation of nasopharyngeal carcinoma with intensity-modulated radiotherapy.

Background and Purpose: To evaluate the treatment outcome in patients with locally recurrent nasopharyngeal carcinoma (NPC) treated with intensity-modulated radiation therapy (IMRT).
Materials and Methods: Between October 2001 and May 2004, 31 patients with locally recurrent NPC received re-irradiation using IMRT. The rT classification distribution was 3 for rT1, 5 for rT2, 9 for rT3, and 14 for r T4. Median time from first course of radiotherapy to re-irradiation was 51 months. IMRT was performed using step-and-shoot method with nine 4-6 MV photon fields and median prescribed dose was 54 Gy (range: 50-60 Gy). Additional treatments included cisplatin-based induction chemotherapy in 68% and radiosurgery boost with a single dose which ranged from 8.5 to 12.5 Gy in 32%. Median follow-up time was 11 months.
Results: After re irradiation, 58% of patients had complete regression of primary tumor. One-year loco-regional progression-free, distant metastasis-free and overall survival rates were 56, 90, and 63%, respectively. Significantly better 1-year local progression-free rate was observed in rT1-3 than r T4 tumor (100 vs. 35%). Grade 3 late toxicities, mostly ototoxicity/cranial neuropathy, occurred in six patients (19%). One-year actuarial rates of late toxicities were 70% for all grades and 25% for Grade 3.
Conclusion: Our preliminary results showed that good control of rT1-3 NPC can be achieved using IMRT with a dose between 50 and 60 Gy, whereas the outcome for r T4 tumor remained poor. Late toxicities were common but incidence of severe toxicities was relatively low.