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
HP, hearing preservation
HR, hazard ratio
PTA, pure tone average
RT, radiation therapy
SD, speech discrimination
SRS, stereotactic radiosurgery
*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: firstname.lastname@example.org
Received December 15, 2012
Accepted May 31, 2013