Small-field fractionated radiotherapy with or without stereotactic boost for vestibular schwannoma.
OBJECTIVE
To assess the efficacy and toxicity of small-field fractionated radiotherapy with or without stereotactic boost (SB) for vestibular schwannomas.


METHODS
Thirty-nine patients with vestibular schwannoma were treated with irradiation between March 1991 and February 1996. Extra-meatal tumor diameters were under 30 mm. Thirty-three patients received small-field fractionated radiotherapy followed by SB. Basic dose schedule was 44 Gy in 22 fractions over 5 1/2 weeks plus 4 Gy in one session. Six patients received small-field fractionated radiotherapy only (40-44 Gy in 20-22 fractions over 5-5 1/2 weeks or 36 Gy in 20 fractions over 5 weeks).dash;p >


RESULTS
Follow-up ranged from 6 to 69 months (median, 24 months). Tumors decreased in size in 13 cases (33%), were unchanged in 25 (64%), and increased in one (3%). The actuarial 2-year tumor control rate was 97%. Fifteen patients had useful hearing (Gardner-Robertson class 1-2) and 25 patients had testable hearing (class 1-4) before irradiation. The 2-year actuarial rates of useful hearing preservation (free of deterioration from class 1-2 to class 3-5) were 78%. The 2-year actuarial rates of any testable hearing preservation (free of deterioration from class 1-4 to class 5) were 96%. No permanent facial and trigeminal neuropathy developed after irradiation. The 2-year actuarial incidences of facial and trigeminal neuropathies were 8% and 16%, respectively.


CONCLUSIONS
Small-field fractionated radiotherapy with or without SB provides excellent short-term local control and a relatively low incidence of complications for vestibular schwannoma, although further follow-up is necessary to evaluate the long-term results.
Kagei
K
K
Department of Radiology, School of Medicine, Hokkaido University, Sapporo, Japan. kkagei@radi.med.hokudai.ac.jp
Shirato
H
H
Suzuki
K
K
Isu
T
T
Sawamura
Y
Y
Sakamoto
T
T
Fukuda
S
S
Nishioka
T
T
Hashimoto
S
S
Miyasaka
K
K
D000206:Actuarial Analysis; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003389:Cranial Nerve Diseases / Q000209:etiology; D018450:Disease Progression; D019583:Dose Fractionation, Radiation; D005155:Facial Nerve Diseases / Q000209:etiology; D005260:Female; D005500:Follow-Up Studies; D006309:Hearing / Q000528:radiation effects; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009442:Neurilemmoma / Q000532:radiotherapy*; D011832:Radiation Injuries / Q000209:etiology; D011880:Radiotherapy Planning, Computer-Assisted; D012074:Remission Induction; D013238:Stereotaxic Techniques; D014276:Trigeminal Nerve / Q000528:radiation effects; D015837:Vestibular Diseases / Q000532:radiotherapy*