A study of middle ear function in the treatment of nasopharyngeal carcinoma with IMRT technique
Received 26 October 2008; received in revised form 16 September 2009; accepted 29 September 2009. published online 23 October 2009.
Abstract
Purpose
This study evaluates the difference in damage to middle ear function with CRT and IMRT techniques in the treatment of nasopharyngeal carcinoma (NPC). We explore the isthmus of the Eustachian tube (ET) as the key anatomic site for the prevention of radiation-induced otitis media with effusion.
Methods and materials
Eighty-two patients with NPC were divided into two groups: 40 patients treated with CRT and 42 patients treated with IMRT. The difference between dosage over the middle ear cavity and the isthmus of the ET was evaluated in both CRT group and IMRT group. All patients underwent hearing tests including pure tone audiometry and impedance audiometry before and after RT.
Results
The dosage difference to the middle ear cavity and isthmus between these two groups was statistically significant (p<0.05). The difference in hearing test results between these two groups was also statistically significant (p<0.05). If we limited the dose to the middle ear cavity under 34Gy and the dose to the isthmus under 53Gy with IMRT, we may decrease radiation-induced OME even with the larger 2.25Gy fraction size.
Conclusions
IMRT may have better protected the middle ear function compared with the CRT technique, even with larger fraction sizes than for the conventional CRT technique.
ABSTRACT