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)

• Published in: Journal of radiation research Vol. 54; no. 4; pp. 727 - 735
• Main Authors: Inoue, Hiroshi K., Seto, Ken-ichi, Nozaki, Akihiko, Torikai, Kota, Suzuki, Yoshiyuki, Saitoh, Jun-ichi, Noda, Shin-ei, Nakano, Takashi
• Format: Journal Article
• Language: English
• Published: England Oxford University Press 01.07.2013
• Subjects: Adult; Aged; Aged, 80 and over; Brain - radiation effects; Brain Edema - diagnosis; Brain Edema - etiology; Brain Neoplasms - diagnosis; Brain Neoplasms - surgery; Female; Humans; Male; Middle Aged; Necrosis; Neoplasm Metastasis - diagnosis; Oncology; Prognosis; Radiation Injuries - diagnosis; Radiosurgery - methods; Reproducibility of Results; Risk; Treatment Outcome; three-session radiosurgery; V14; radiation necrosis; hypofractionated radiotherapy; brain metastases
• ISSN: 0449-3060; 1349-9157
• DOI: 10.1093/jrr/rrt006

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 cm3 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 cm3. There were 35 lesions with a V14 of 7 cm3 or more and three of them developed extensive brain edema due to radiation necrosis. None of the patients with a V14 of <7 cm3 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.