Small-field fractionated radiotherapy with or without stereotactic boost for vestibular schwannoma

Purpose : To assess the efficacy and toxicity of small-field fractionated radiotherapy with or without stereotactic boost (SB) for vestibular schwannomas. Methods and materials : 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). 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.