HAYASHI Motohiro    Department   School of Medicine(Tokyo Women's Medical University Hospital), School of Medicine    Position   Professor
Article types	Original article
Language	English
Peer review	Peer reviewed
Title	Malignant progression of benign brain tumors after gamma knife radiosurgery: is it really caused by irradiation?
Journal	Formal name：Minim Invasive Neurosurg ISSN code：09467211
Domestic / Foregin	Foregin
Publisher	© Georg Thieme Verlag Stuttgart · New York
Volume, Issue, Page	48(6),pp.334-339
Author and coauthor	KUBO Osami, CHERNOV Mikhail, IZAWA Masahiro, HAYASHI Motohiro, MURAGAKI Yoshihiro†, MARUYAMA Takashi, HORI Tomokatsu, TAKAKURA Kintomo
Publication date	2005/12
Summary	Malignant transformation of benign neoplasm after radiosurgery is usually diagnosed based on the initial presence of benign tumor, its exposure to ionizing radiation, elapsed time from radiation exposure to malignant progression, and different histological characteristics or growth rate of the regrowing tumor comparing with those originally treated. Three presented cases fulfilled these diagnostic criteria; however, it seems that progression of the tumors (schwannoma, meningioma, chordoma) resulted from the natural course of the disease, rather than represented side effects of gamma knife radiosurgery. Evaluation of the proliferative potential of the benign neoplasm before radiosurgical treatment either directly, if tumor sampling is available, or indirectly, by calculation of the tumor growth rate and/or analysis of the data of the metabolic imaging (PET, MRS) is important for identification of"aggressive"subtypes, precise prediction of prognosis, and confirmation of the radiation-induced malignant transformation in cases of tumor regrowth.
DOI	10.1055/s-2005-915632
PMID	16432782