Immunohistochemical evaluation of O6-methylguanine DNA methyltransferase (MGMT) expression in 117 cases of glioblastoma

Masaya Miyazaki, Hiroshi Nishihara, Shunsuke Terasaka, Hiroyuki Kobayashi, Shigeru Yamaguchi, Tamio Ito, Yuuta Kamoshima, Shin Fujimoto, Sadao Kaneko, Masahito Katoh, Nobuaki Ishii, Hiromi Mohri, Mishie Tanino, Taichi Kimura, Shinya Tanaka

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14 Citations (Scopus)

Abstract

Temozolomide (TMZ) is an oral alkylating agent which is widely used in the treatment of glioblastoma (GBM) and is composed of astrocytic and/or oligodendroglial tumors, and the evaluation of O6-methylguanine DNA methyltransferase (MGMT) expression is important to predict the response to TMZ therapy. In this study, we conducted immunohistochemical analysis of 117 cases of Japanese GBM including 19 cases of GBM with oligodendroglioma component (GBMO), using a scoring system for quantitative evaluation of staining intensity and proportion of MGMT, and performed survival analysis of these patients. Immunohistochemically, 55 cases (47%) were positive for MGMT with various intensities and proportions (total score (TS)≥2), while 62 cases (53%) were negative (TS=0). The distribution of MGMT expression pattern was not affected by any clinicopathological parameters such as the histological subtype (GBM vs. GBMO), age and gender. The survival analysis of these patients revealed that the minimal expression of MGMT (TS≥2) was a significant unfavorable prognostic factor (P<0.001) as well as resectability (P=0.004). Moreover, multivariate analysis showed that minimal MGMT expression in GBM was the most potent independent predictor for progression free survival (P<0.001) and also overall patient survival (P<0.001). This is the first report employing the scoring system for both staining intensity and proportion to evaluate immunohistochemical MGMT expression in GBM. In addition, our results emphases the clinicopathological values of the immunohistochemical approach for MGMT expression in glioma patients as a routine laboratory examination.

Original languageEnglish
Pages (from-to)268-276
Number of pages9
JournalNeuropathology
Volume34
Issue number3
DOIs
Publication statusPublished - 2014 Jun
Externally publishedYes

Keywords

  • Glioblastoma
  • Immunohistochemistry
  • MGMT
  • Survival analysis
  • Temozolomide

ASJC Scopus subject areas

  • Pathology and Forensic Medicine
  • Clinical Neurology

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    Miyazaki, M., Nishihara, H., Terasaka, S., Kobayashi, H., Yamaguchi, S., Ito, T., Kamoshima, Y., Fujimoto, S., Kaneko, S., Katoh, M., Ishii, N., Mohri, H., Tanino, M., Kimura, T., & Tanaka, S. (2014). Immunohistochemical evaluation of O6-methylguanine DNA methyltransferase (MGMT) expression in 117 cases of glioblastoma. Neuropathology, 34(3), 268-276. https://doi.org/10.1111/neup.12091