A study of middle ear function in the treatment of nasopharyngeal carcinoma with IMRT technique.
OBJECTIVE
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
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 34 Gy and the dose to the isthmus under 53 Gy with IMRT, we may decrease radiation-induced OME even with the larger 2.25 Gy 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.
Department of Radiation Oncology, Eye, Ear, Nose and Throat Hospital of Fudan University, Shanghai, China. shengziwang@fudan.edu.cn
Sheng Zi
SZ
Wang
Ji
J
Li
Curtis T
CT
Miyamoto
Fu
F
Chen
Li Fen
LF
Zhou
Hai Yan
HY
Zhang
Gang
G
Yang
Wei Fang
WF
Wang
Ming
M
Guo
Xiao Chen
XC
Ni
Lei
L
Wang
D001299:Audiometry; D002277:Carcinoma / Q000532:radiotherapy*; D004432:Ear, Middle / Q000503:physiopathology / Q000528:radiation effects*; D005064:Eustachian Tube / Q000528:radiation effects; D005260:Female; D034381:Hearing Loss / Q000209:etiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009303:Nasopharyngeal Neoplasms / Q000532:radiotherapy*; D010034:Otitis Media with Effusion / Q000209:etiology; D011829:Radiation Dosage; D011832:Radiation Injuries; D011879:Radiotherapy Dosage; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects