• Janjira Petsuksiri, Achariyaporn Sermsree, Kullathorn Thephamongkhol, Phawin Keskool, Kanthong Thongyai, Yaowalak Chansilpa, and Pittayapoom Pattaranutaporn.
• Division of Radiation Oncology, Faculty of Medicine Siriraj Hospital, 2 Prannok Rd, Bangkoknoi, Bangkok, Thailand. sijps@mahidol.ac.th
• Radiat Oncol. 2011 Feb 20; 6: 19.

BackgroundSensorineural hearing loss (SNHL) is one of the major long term side effects from radiation therapy (RT) in nasopharyngeal cancer (NPC) patients. This study aims to review the incidences of SNHL when treating with different radiation techniques. The additional objective is to determine the relationship of the SNHL with the radiation doses delivered to the inner ear.MethodsA retrospective cohort study of 134 individual ears from 68 NPC patients, treated with conventional RT and IMRT in combination with chemotherapy from 2004-2008 was performed. Dosimetric data of the cochlea were analyzed. Significant SNHL was defined as >15 dB increase in bone conduction threshold at 4 kHz and PTA (pure tone average of 0.5, 1, 2 kHz). Relative risk (RR) was used to determine the associated factors with the hearing threshold changes at 4 kHz and PTA.ResultsMedian audiological follow up time was 14 months. The incidence of high frequency (4 kHz) SNHL was 44% for the whole group (48.75% in the conventional RT, 37% with IMRT). Internal auditory canal mean dose of >50 Gy had shown a trend to increase the risk of high frequency SNHL (RR 2.02 with 95% CI 1.01-4.03, p=0.047).ConclusionIMRT and radiation dose limitation to the inner ear appeared to decrease SNHL.

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