Hypofractionated stereotactic radiotherapy for acoustic neuromas: safety and effectiveness over 8 years of experience.
BACKGROUND
Little information is available about long-term outcomes of hypofractionated stereotactic radiotherapy (hypo-FSRT) for acoustic neuromas. In this study, the safety and effectiveness of hypo-FSRT for unilateral acoustic neuroma were reviewed over 8 years of experience at our institution.


METHODS
Between May 1998 and October 2006, 27 patients were consecutively treated by linear accelerator-based hypo-FSRT. Two patients were excluded from this study because they were lost to follow-up within 12 months. The median follow-up period for the rest was 59 (range 24-133) months. Two types of treatment schedules were adopted. Thirteen patients received 30-39 Gy, given in 10-13 fractions (regimen A), whereas after July 2003, 12 patients received 20-24 Gy, given in 5-6 fractions at the tumor periphery (regimen B). These treatments were scheduled to be delivered in three fractions per week (Monday, Wednesday, Friday). The median planning target volume was 2.0, with 1.7 ml (range 0.7-10.6) in regimen A and 5.2 ml (range 0.9-9.3) in regimen B. In the pretreatment audiogram, seven patients (two in regimen A and five in regimen B) had serviceable hearing (Gardner-Robertson Class I-II).


RESULTS
Local control rates were 100% with regimen A and 92% with regimen B. Serviceable hearing was preserved in four of five patients in regimen B but no patients in regimen A at the last follow-up. No permanent facial or trigeminal nerve morbidity was observed following treatment, and no salvage surgery was needed.


CONCLUSIONS
Hypo-FSRT for acoustic neuromas achieved a high local control rate with minimal facial and trigeminal nerve morbidity.
Sakanaka
Katsuyuki
K
Department of Radiation Oncology and Image-applied Therapy, Kyoto University Graduate School of Medicine, 54 Sho-goin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan.
Mizowaki
Takashi
T
Arakawa
Yoshiki
Y
Araki
Norio
N
Oya
Natsuo
N
Takahashi
Jun A
JA
Mikuni
Nobuhiro
N
Miyamoto
Susumu
S
Hashimoto
Nobuo
N
Hiraoka
Masahiro
M
D000328:Adult; D000368:Aged; D019583:Dose Fractionation, Radiation; D005260:Female; D006320:Hearing Tests; D006801:Humans; D008297:Male; D008875:Middle Aged; D009464:Neuroma, Acoustic / Q000503:physiopathology / Q000532:radiotherapy*; D016634:Radiosurgery / Q000009:adverse effects / Q000379:methods*; D016896:Treatment Outcome