title: Radiation-Induced Meningiomas: An Exhaustive Review of the Literature.
abstract: OBJECTIVE
  Radiation-induced meningioma (RIM) is an uncommon late risk of cranial irradiation. We conducted an exhaustive review of individual patient data to characterize RIM.
  
  
  METHODS
  Using a systematic search of the PubMed database, we performed a comprehensive literature review to characterize and investigate RIM. Student t tests were used to evaluate differences between variables. A Kaplan-Meier analysis was used to assess survival. Statistical significance was assessed using a log-rank test.
  
  
  RESULTS
  Our analysis included 251 cases of RIM. The average age at onset for the primary lesion was 13.0 ± 13.5 years, and the average radiation dose delivered to this lesion was 38.8 ± 16.8 Gy. Secondary meningiomas could be divided into grades I (140), II (55), and III (10) tumors. Thirty patients (11.9%) had multiple lesions, and 46 (18.3%) had recurrent meningiomas. The latency period between radiotherapy for primary lesions and the onset of meningiomas was 22.9 ± 11.4 years. The latency period was shorter for patients with grade III meningioma and for those in the high-dose and intermediate-dose radiation groups who received systemic chemotherapy. Aggressive meningiomas and multiple meningiomas were more common in the high-dose and intermediate-dose groups than in the low-dose group. The 5-year and 10-year survival rates for all patients with meningioma were 77.7% and 66.1%, respectively.
  
  
  CONCLUSIONS
  For patients treated with cranial radiotherapy, the risk of secondary meningioma warrants a longer follow-up period beyond the standard time frame typically designated for determining the risk of primary tumor relapse.
authors.affiliation: Laboratory of Molecular Target Therapy for Cancer, Graduate School for Medical Science, Kyoto Prefectural University of Medicine, Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto, Japan. Electronic address: ryaman@koto.kpu-m.ac.jp.
authors.forename: Ryuya
authors.initials: R
authors.lastname: Yamanaka
authors.affiliation: Laboratory of Molecular Target Therapy for Cancer, Graduate School for Medical Science, Kyoto Prefectural University of Medicine, Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto, Japan.
authors.forename: Azusa
authors.initials: A
authors.lastname: Hayano
authors.affiliation: Laboratory of Molecular Target Therapy for Cancer, Graduate School for Medical Science, Kyoto Prefectural University of Medicine, Kawaramachi-Hirokoji, Kamigyo-ku, Kyoto, Japan.
authors.forename: Tomohiko
authors.initials: T
authors.lastname: Kanayama
mesh_terms: D000293:Adolescent; D000328:Adult; D017668:Age of Onset; D001932:Brain Neoplasms / Q000532:radiotherapy*; D002648:Child; D016371:Cranial Irradiation / Q000009:adverse effects*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D060787:Neoplasm Grading; D009378:Neoplasms, Multiple Primary / Q000175:diagnosis* / Q000473:pathology / Q000601:surgery*; D009381:Neoplasms, Radiation-Induced / Q000175:diagnosis* / Q000473:pathology / Q000601:surgery*; D011829:Radiation Dosage; D012307:Risk Factors; D055815:Young Adult
keywords: Meningioma; Radiation-induced meningioma; Radiotherapy