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Revista médica de Chile

Print version ISSN 0034-9887


JIMENEZ, Daniel et al. O6-methylguanine-DNA-methyltransferase (MGMT) expression in patients with glioblastoma multiforme. Rev. méd. Chile [online]. 2018, vol.146, n.1, pp.7-14. ISSN 0034-9887.


Patients with Glioblastoma multiforme (GBM) have a five years survival of less than 5%, but the response to chemotherapy with alkylating agents can vary depending on the methylation status of O6-methylguanine-DNA-methyltransferase (MGMT). Genetic testing has limitations for routine use, while immunohistochemistry (IHC) offers a fast and affordable technique but with heterogeneous results in the literature.


To evaluate MGMT expression by IHC in tumor tissue of Chilean patients with GBM.

Material and Methods:

Tumor samples of 29 patients with a pathological diagnosis of GBM were studied. We performed IHC staining and manual analysis of positive and negative cells for MGMT expression. A cut-off of at least 10% of cells expressing MGMT was used. Demographic and clinical features of patients were obtained from clinical records.


The median number of cells counted per case was 692 (interquartile range [IQR] 492-928). Fifteen cases (52%) were positive for MGMT expression. Median overall survival was 5.3 months (IQR 3.4-12-8). The effect of MGMT expression on the therapeutic response was not studied since only 3 patients received chemotherapy.


Our results are similar to international reports, but we were not able to determine the association between MGMT expression and therapeutic response.

Keywords : Glioblastoma; Immunohistochemistry; O6-Methylguanine-DNA-Methyltransferase; Prognosis.

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