立体定向放射外科和分次立体定向放射治疗前庭神经鞘瘤后，耳蜗放射剂量增加可预测听力延迟损失。
Increased cochlear radiation dose predicts delayed hearing loss following both stereotactic radiosurgery and fractionated stereotactic radiotherapy for vestibular schwannoma.
机构信息
Department of Neurosurgery, University of California Los Angeles, Los Angeles, USA.
Department of Head and Neck Surgery, University of California Los Angeles, Los Angeles, CA, USA.
出版信息
J Neurooncol. 2019 Nov;145(2):329-337. doi: 10.1007/s11060-019-03299-5. Epub 2019 Sep 24.
PURPOSE
Stereotactic radiosurgery (SRS) and fractionated stereotactic radiotherapy (fSRT) are noninvasive therapies for vestibular schwannomas providing excellent tumor control. However, delayed hearing loss after radiation therapy remains an issue. One potential target to for improving hearing rates is limiting radiation exposure to the cochlea.
METHODS
We retrospectively reviewed 100 patients undergoing either SRS with 12 Gy (n = 43) or fSRT with 50 Gy over 28 fractions (n = 57) for vestibular schwannoma. Univariate and multivariate analysis were carried out to identify predictors of hearing loss as measured by the Gardner Robertson scale after radiation therapy.
RESULTS
Deterioration of hearing occurred in 30% of patients with SRS and 26% with fSRT. The overall long term (> 2 year) progression rates were 20% for SRS and 16% for fSRT. Patients with a decrease in their Gardner Robertson hearing score and those that loss serviceable hearing had significantly higher average minimal doses to the cochlea in both SRS and fSRT cohorts. ROC analysis showed that a cut off of 5 Gy and 35 Gy, for SRS and fSRT respectively, predicted hearing loss with high sensitivity/specificity.
CONCLUSION
Our data suggests the minimal dose of radiation that the cochlear volume is exposed to is a predictor of delayed hearing loss after either SRS or fSRT. A threshold of 5 Gy/35 Gy may lead to improved hearing preservation after radiotherapy. Further prospective multi center studies can further elucidate this mechanism.
目的
立体定向放射外科（SRS）和分次立体定向放射治疗（fSRT）是治疗前庭神经鞘瘤的非侵入性治疗方法，可提供出色的肿瘤控制效果。然而，放射治疗后出现的迟发性听力损失仍然是一个问题。提高听力的一个潜在目标是限制耳蜗的辐射暴露。
方法
我们回顾性分析了 100 例接受 SRS（12 Gy，n = 43）或 fSRT（50 Gy，28 次分割，n = 57）治疗前庭神经鞘瘤的患者。进行单变量和多变量分析，以确定放射治疗后听力损失（根据 Gardner Robertson 量表测量）的预测因素。
结果
SRS 组中有 30%的患者和 fSRT 组中有 26%的患者听力下降。SRS 和 fSRT 的长期（> 2 年）进展率分别为 20%和 16%。在 SRS 和 fSRT 两组中，听力评分下降和丧失可利用听力的患者耳蜗的平均最小剂量明显更高。ROC 分析表明，SRS 和 fSRT 的最小剂量分别为 5 Gy 和 35 Gy 时，可预测听力损失，具有较高的灵敏度/特异性。
结论
我们的数据表明，耳蜗体积所受的辐射最小剂量是 SRS 或 fSRT 后迟发性听力损失的预测因素。5 Gy/35 Gy 的阈值可能会提高放射治疗后的听力保护效果。进一步的前瞻性多中心研究可以进一步阐明这一机制。
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