title: Significance of target location relative to the depth from the brain surface and high-dose irradiated volume in the development of brain radionecrosis after micromultileaf collimator-based stereotactic radiosurgery for brain metastases.
abstract: The objective of this study was to investigate the factors that potentially lead to brain radionecrosis (RN) after micromultileaf collimator-based stereotactic radiosurgery (SRS) for brain metastases. We retrospectively evaluated 131 lesions with a minimum follow-up of 6 months, 43.5% of which received prior whole-brain radiotherapy (WBRT). The three-tiered location grade (LG) was defined, as follows, for each target by considering mainly the depth from the brain surface: grade 1 (superficial), involving the region at a depth of ≤5 mm from the brain surface; grade 2 (deep), located at a depth of >5 mm from the brain surface; and grade 3 (central), located in the brainstem, cerebellar peduncle, diencephalon, or basal ganglion. The predictive factors for RN, including high-dose irradiated isodose volumes (IIDVs) and LG, were evaluated by univariate and multivariate analysis. Symptomatic RN (S-RN) and asymptomatic RN (A-RN) were observed in 8.4% and 6.9% of cases, respectively. Multivariate analysis indicated that the significant factors for both types of RN were LG, V12 Gy, and V22 Gy in all cases; V22 Gy and LG for the non-WBRT cases; and V15 Gy and LG for the WBRT cases. For the non-WBRT cases, the cutoff values of V22 Gy were 2.62 and 2.14 cm(3) for S-RN and both RN, respectively. For the WBRT cases, the cutoff values of V15 Gy were 5.61 and 5.20 cm(3) for S-RN and both RN, respectively. In addition to the IIDV data, LG helps predict the risk of RN. High-dose IIDV, V22 Gy, was also significantly correlated with RN, particularly for patients treated with SRS alone.
authors.affiliation: Department of Radiology, Gifu University Graduate School of Medicine, 1-1 Yanagido, Gifu, 501-1194, Japan. ohtakara@gifu-u.ac.jp
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Ohtakara
authors.forename: Shinya
authors.initials: S
authors.lastname: Hayashi
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Nakayama
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Ohe
authors.forename: Hirohito
authors.initials: H
authors.lastname: Yano
authors.forename: Toru
authors.initials: T
authors.lastname: Iwama
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Hoshi
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000970:Antineoplastic Agents / Q000627:therapeutic use; D019540:Area Under Curve; D001921:Brain / Q000473:pathology*; D001932:Brain Neoplasms / Q000188:drug therapy / Q000556:secondary* / Q000601:surgery*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009336:Necrosis; D012372:ROC Curve; D011832:Radiation Injuries / Q000209:etiology* / Q000473:pathology*; D016634:Radiosurgery / Q000009:adverse effects*; D011879:Radiotherapy Dosage; D012189:Retrospective Studies; D016896:Treatment Outcome
chemical_list: D000970:Antineoplastic Agents