title: Three-fraction CyberKnife radiotherapy for brain metastases in critical areas: referring to the risk evaluating radiation necrosis and the surrounding brain volumes circumscribed with a single dose equivalence of 14 Gy (V14).
abstract: The efficacy and toxicity of three-fraction CyberKnife radiotherapy were evaluated in patients with brain metastases in critical areas. One hundred and fifty-nine metastases in 145 patients including tumors >10 cm(3) were treated with three-fraction CyberKnife radiotherapy with a median marginal dose of 27 Gy at a median prescribed isodose of 60%. Changes in the neurological manifestations, local tumor control and adverse effects were investigated after treatment. The surrounding brain volumes circumscribed with 23.1 Gy (single dose equivalence of 14 Gy: V14) were measured to evaluate the risk of adverse effects. Neurological manifestations, such as motor weakness, visual disturbances and aphasia improved in 26 of 97 patients (26.8%). Local tumor control was obtained in 137 of 143 metastases (95.8%) during a median follow-up of 7 months. Nine patients had symptomatic edema and three of them (2.1%) required surgical resection because of radiation necrosis. The V14 of these patients was 4.6-31.5 cm(3). There were 35 lesions with a V14 of 7 cm(3) or more and three of them developed extensive brain edema due to radiation necrosis. None of the patients with a V14 of <7 cm(3) exhibited edema requiring an operation. We therefore conclude that a high rate of local tumor control and low rates of complications are obtained after three-fraction CyberKnife radiotherapy for metastases in critical areas. The V14 of the surrounding brain therefore seems to be a useful indicator for the risk evaluation of radiation necrosis in patients with larger metastases.
authors: Cyber Center, Kanto Neurosurgical Hospital, 1120 Dai, Kumagaya, Saitama, 360-0804, Japan. chair.ino@instno-med.org
authors: Hiroshi K
authors: HK
authors: Inoue
authors: Ken-Ichi
authors: K
authors: Seto
authors: Akihiko
authors: A
authors: Nozaki
authors: Kota
authors: K
authors: Torikai
authors: Yoshiyuki
authors: Y
authors: Suzuki
authors: Jun-Ichi
authors: J
authors: Saitoh
authors: Shin-Ei
authors: SE
authors: Noda
authors: Takashi
authors: T
authors: Nakano
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001921:Brain / Q000528:radiation effects; D001929:Brain Edema / Q000175:diagnosis / Q000209:etiology; D001932:Brain Neoplasms / Q000175:diagnosis / Q000601:surgery*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009336:Necrosis; D009362:Neoplasm Metastasis / Q000175:diagnosis*; D011379:Prognosis; D011832:Radiation Injuries / Q000175:diagnosis*; D016634:Radiosurgery / Q000379:methods*; D015203:Reproducibility of Results; D012306:Risk; D016896:Treatment Outcome
keywords: V14; brain metastases; hypofractionated radiotherapy; radiation necrosis; three-session radiosurgery
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