6036 Background: Xerostomia is ubiquitous after conventional radiotherapy (CRT) for nasopharyngeal carcinoma (NPC). Intensity modulated radiotherapy (IMRT) has been advocated to spare the parotids for early disease. However, in T2 disease where there is a need to cover parapharyngeal involvement, it is uncertain if IMRT can still preserve salivary function without compromising local control. Methods: Patients with T2N0/1M0 NPC to be treated with RT alone were eligible. Patients were randomized to receive CRT or IMRT. The end points were salivary flow and local control. 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. Results: From 2000 to 2005, 42 and 40 patients were randomized to IMRT and CRT respectively. 19 (47.5%) and 27 (64.3%) of patients treated with CRT and IMRT had N1 disease respectively (p=0.18). The median dose for CRT patients was 68 Gy and 75% patients received additional parapharyngeal boost dose of 10 Gy. The median dose to NP for patient treated with IMRT was 70 Gy with no additional boost. Disease control and survival rates were shown in the Table. 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 CRT showed no improvement over time. The mean SWS and SPS flow at 12 months were 26% and 114% of baseline among patients treated with IMRT, compared with 5% and 0% among patients treated with CRT. There was significant difference in SWS and SPS between patients treated with IMRT and CRT at 2, 6 and 12 months post-RT. The average mean dose to parotid gland was 41Gy. Conclusions: IMRT can reserve salivary flow despite a relatively high mean dose to the parotid glands. The significant improvement in local control with IMRT was unexpected but can be due to better coverage of disease with 3-dimensional planning. No significant financial relationships to disclose.
Comparison of the efficacy between intensity-modulated radiotherapy and two-dimensional conventional radiotherapy in stage II nasopharyngeal carcinoma
