Turkish Neurosurgery
Microsatellite Instability in Glioblastoma: Is it really relevant in tumor prognosis?
Merih Tepeoğlu1, Pelin Börcek1, Özlem Özen1, Mehmet Nur Altınörs2
1Baskent University, Pathology, Ankara,
2Baskent University, Neurosurgery, Ankara,
DOI: 10.5137/1019-5149.JTN.27333-19.1

Aim:DNA mismatch repair (MMR) system functions in maintaining DNA homeostasis and is involved in the repair of specific types of errors that occur during DNA replication in dividing somatic cells. Microsatellite instability (MSI) indicates defective DNA MMR proteins, which result in variable microsatellite sequences. MSI is believed to have a prognostic effect in various tumors. Here, immunohistochemical analysis of MMR proteins was performed to evaluate the frequency and prognostic significance of MSI in patients with glioblastoma (GBM).Material and Methods:We included 71 patients with GBM who underwent surgery between 2011 and 2019 at Baskent University, Department of Neurosurgery. MMR protein expression was examined using immunohistochemistical analysis of tumor tissue samples; the association between the MMR status and clinicopathological findings was evaluated.Results:Immunohistochemical analysis revealed expressions of MLH1, MSH2, MSH6, and PMS2 proteins in 67 (94.4%), 65 (91.5%), 67 (94.4%), and 64 (90.1%) patients, respectively. Among the 71 patients, 64 (90.1%) expressing all MMR proteins were considered microsatellite stable (MSS) and 7 (9.9%) patients showing loss of at least one of the MMR proteins were considered to show MSI. Tumor recurrence was noted in 25 (39.1%) patients in the MSS GBM group and 4 (57.1%) patients in the MSI GBM group (p = 0.433). The overall survival was 30.65 ± 5.1 and 10.71 ± 5.2 months in the MSS GBM and MSI GBM groups, respectively (p = 0.059).Conclusion:No significant relationships were noted between MMR protein expression and recurrence rates or overall survival in patients with GBM.

Corresponding author : Merih Tepeoğlu