Impact of the Mean Cochlear Biologically Effective Dose on Hearing Preservation After Stereotactic Radiosurgery for Vestibular Schwannoma: A Retrospective Longitudinal Analysis

• BACKGROUND AND OBJECTIVES: Stereotactic radiosurgery (SRS) is a useful alternative for small- to medium-sizedvestibular schwannoma. To evaluate whether biologically effective dose (BEDGy2.47), calculated for mean (BEDGy2.47 mean)and maximal (BEDGy2.47 max) cochlear dose, is relevant for hearing preservation. METHODS: This is a retrospective longitudinal single-center study. Were analyzed 213 patients with useful baselinehearing. Risk of hearing decline was assessed for Gardner–Robertson classes and pure tone average (PTA) loss. The meanfollow-up period was 39 months (median 36, 6-84).RESULTS: Hearing decline (Gardner–Robertson class) 3 years after SRS was associated with higher cochlear BEDGy2.47 mean(odds ratio [OR] 1.39, P = .009). Moreover, BEDGy2.47 mean was more relevant as compared with BEDGy2.47 max (OR 1.13, P = .04).Risk of PTA loss (continuous outcome, follow-up minus baseline) was significantly corelated with BEDGy2.47 mean at 24 (betacoefficient 1.55, P = .002) and 36 (beta coefficient 2.01, P = .004) months after SRS. Risk of PTA loss (>20 dB vs ≤) was associatedwith higher BEDGy2.47 mean at 6 (OR 1.36, P = .002), 12 (OR 1.36, P = .007), and 36 (OR 1.37, P = .02) months. Risk of hearingdecline at 36 months for the BEDGy2.47 mean of 7–8, 10, and 12 Gy2.47 was 28%, 57%, and 85%, respectively. CONCLUSION: Cochlear BEDGy2.47 mean is relevant for hearing decline after SRS and more relevant as compared withBEDGy2.47 max. Three years after SRS, this was sustained for all hearing decline evaluation modalities. Our data suggestthe BEDGy2.47 mean cut-off of ≤8 Gy2.47 for better hearing preservation rates.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Cancer och onkologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Cancer and Oncology (hsv//eng)

Nyckelord

Biologically effective dose

Cochlea

Hearing preservation

Vestibular schwannoma

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