Division of Radiation Oncology, Faculty of Medicine Siriraj Hospital, 2 Prannok Rd, Bangkoknoi, Bangkok, Thailand.
Radiat Oncol. 2011 Feb 20;6:19. doi: 10.1186/1748-717X-6-19.
Sensorineural 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.
A 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.
Median 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).
IMRT and radiation dose limitation to the inner ear appeared to decrease SNHL.
感音神经性听力损失（SNHL）是鼻咽癌（NPC）患者放射治疗（RT）的主要长期副作用之一。本研究旨在回顾不同放射技术治疗时 SNHL 的发生率。另外的目的是确定 SNHL 与内耳接受的放射剂量之间的关系。
对 2004 年至 2008 年间接受常规 RT 和调强放疗（IMRT）联合化疗的 68 例 NPC 患者的 134 只耳朵进行回顾性队列研究。对耳蜗的剂量学数据进行分析。将 >15dB 的骨导阈值在 4kHz 和 PTA（0.5、1、2kHz 的纯音平均听阈）处的增加定义为显著 SNHL。使用相对风险（RR）来确定与 4kHz 和 PTA 听力阈值变化相关的因素。
中位听力随访时间为 14 个月。全组高频（4kHz）SNHL 的发生率为 44%（常规 RT 组为 48.75%，IMRT 组为 37%）。内听道平均剂量>50Gy 显示出增加高频 SNHL 的风险趋势（RR 2.02，95%CI 1.01-4.03，p=0.047）。
IMRT 和内耳放射剂量限制似乎可降低 SNHL。
