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Reduced-Dose Fractionated Stereotactic Radiotherapy for Acoustic Neuromas: Maintenance of Tumor Control With Improved Hearing Preservation

Champ, Colin E. MD*; Shen, Xinglei MD; Shi, Wenyin MD, PhD*; Mayekar, Sonal U.*; Chapman, Katherine*; Werner-Wasik, Maria MD*; Farrell, Christopher J. MD§; Gunn, Vicki*; Downes, M. Beverly MS§; Liu, Haisong PhD*; Evans, James J. MD§; Andrews, David W. MD§

Neurosurgery:
doi: 10.1227/NEU.0000000000000019
Research-Human-Clinical Studies
Abstract

BACKGROUND: Fractionated stereotactic radiotherapy (FSRT) is a noninvasive treatment for acoustic neuromas (ANs). Initial reports from our institution demonstrated that the reduction of treatment dose to 46.8 Gy resulted in improved preservation of functional hearing status.

OBJECTIVE: We now report the tumor control (TC), symptomatic outcome, and hearing preservation (HP) rate in patients treated with reduced-dose FSRT.

METHODS: We analyzed all patients with AN treated from 2002 to 2011. All patients received 46.8 Gy in 1.8-Gy fractions. Follow-up audiogram and magnetic resonance imaging were performed in ≤1-year intervals. TC and HP were calculated by the Kaplan-Meier method. Analysis of HP, defined as Gardner-Robertson value ≤2, was determined by audiometric data. Non-hearing-related symptoms were defined by Common Terminology Criteria for Adverse Events version 4.

RESULTS: In total, 154 patients were analyzed. At a median follow-up of 35 months (range, 4-108), TC was achieved in 96% of patients (n = 148/154) and at 3 and 5 years was 99% and 93%. Eighty-seven patients had serviceable hearing at the time of FSRT and evaluable audiometric follow-up. Overall HP was 67% and at 3 and 5 years was 66% and 54%. Pure tone average decreased by a median of 13 dB in all patients. Nineteen percent (n = 31) of patients experienced symptom improvement, and 8% (n = 13) had worsening of symptoms. Cranial nerve dysfunction occurred in 3.8% of patients (n = 6).

CONCLUSION: Reduced-dose FSRT to 46.8 Gy for AN achieves excellent functional HP rates and limited toxicity without compromising long-term TC. Based on these promising outcomes, further attempts at dose deescalation may be warranted.

ABBREVIATIONS: AN, acoustic neuromas

FSRT, fractionated stereotactic radiotherapy

GR, Gardner-Robertson

HP, hearing preservation

HR, hazard ratio

KM, Kaplan-Meier

PTA, pure tone average

RT, radiation therapy

SD, speech discrimination

SRS, stereotactic radiosurgery

Author Information

*Department of Radiation Oncology, Kimmel Cancer Center and Jefferson Medical College of Thomas Jefferson University, Philadelphia, Pennsylvania;

Department of Radiation Oncology, University of Kansas Medical Center, Kansas City, Kansas;

§Department of Neurological Surgery, Kimmel Cancer Center and Jefferson Medical College of Thomas Jefferson University, Philadelphia, Pennsylvania

Correspondence: Colin E. Champ, MD, Kimmel Cancer Center and Jefferson Medical College of Thomas Jefferson University, 111 S 11th St, Philadelphia, PA 19107. E-mail: colinchamp@gmail.com

Received December 15, 2012

Accepted May 31, 2013

Copyright © by the Congress of Neurological Surgeons