Abstract
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.
Highlights
Sensorineural hearing loss (SNHL) is one of the major long term side effects from radiation therapy (RT) in nasopharyngeal cancer (NPC) patients
This retrospective analytic study aims to report the incidences of SNHL of NPC patients receiving chemoradiotherapy with conventional RT comparing with intensity modulated radiation therapy (IMRT)
As most earlier studies had some disagreement about the cochlea contouring for dose volume analysis, the further aim of this study is to evaluate radiation doses in each specific part of the inner ear [cochlea, inner ear and internal auditory canal (IAC)] in correlation with the incidences of SNHL
Summary
Sensorineural hearing loss (SNHL) is one of the major long term side effects from radiation therapy (RT) in nasopharyngeal cancer (NPC) patients. With modern conformal radiation techniques, the incidence of radiation induced SNHL is expected to decline, due to a better visualization of the organs on the planning CT images and a better capability to spare the cochlea with a mean dose < 40-50 Gy [4,5,6,7]. This retrospective analytic study aims to report the incidences of SNHL of NPC patients receiving chemoradiotherapy with conventional RT comparing with intensity modulated radiation therapy (IMRT). As most earlier studies had some disagreement about the cochlea contouring for dose volume analysis, the further aim of this study is to evaluate radiation doses in each specific part of the inner ear [cochlea, inner ear (cochlea and vestibule) and internal auditory canal (IAC)] in correlation with the incidences of SNHL
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