A randomized trial comparing intensity modulated radiotherapy versus 2-dimensional radiotherapy for stage II nasopharyngeal carcinoma

Abstract

PURPOSE/OBJECTIVE(S): To compare, in a randomized trial, the disease control and salivary function in stage II nasopharyngeal carcinoma (NPC) patients treated with intensity modulated radiotherapy (IMRT) vs. 2-dimensional radiotherapy (2DRT). MATERIALS/METHODS: T2N0/1M0 NPC patients with neck node4cm, to be treated with RT alone were eligible. Patients were randomized to receive 2DRT or IMRT. The end points were local control and salivary flow. Persistent disease after RT and NP recurrence are considered local failures. The goal was non-inferiority of local control. For salivary function assessment, the aim was to recruit 25 patients for salivary flow study in each arm. All patients underwent stimulated parotid (SPS) and whole salivary (SWS) flow assessment before RT and at 2, 6, and 12 months after RT. The study was reviewed and stopped after 60 patients had completed 1 year post-RT assessment. RESULTS: From 2000 to 2005, 42 and 40 patients were randomized to IMRT and 2DRT, respectively. The median follow-up was 54 months. 19 (47.5%) and 27 (64.3%) of patients treated with 2DRT and IMRT had N1 disease, respectively (p = 0.18). The median dose for 2DRT patients was 68Gy and 75% patients received additional 10Gy parapharyngeal boost. The median dose to NP for patient treated with IMRT was 70Gy with no additional boost. 4 year local control was 90.5% with IMRT vs. 71.7% with 2DRT (p = 0.019). Neck control, distant metastasis, failure-free, and disease specific survival were not significantly different between the 2 arms. 25 patients in each arm underwent prospective salivary flow assessment. There was gradual recovery of SWS and SPS among patients treated with IMRT while patient on 2DRT showed no improvement over time. The mean SWS and SPS flow at 12 months was 26% and 114% of baseline among patients treated with IMRT, compared with 5% and 0% among patients treated with 2DRT, respectively. There was significant difference in SWS and SPS between patients treated with IMRT and 2DRT at 2, 6, and 12 months post-RT. The average mean dose to parotid gland with IMRT was 41Gy. CONCLUSIONS: IMRT achieved better local control than 2DRT and preserves salivary function.