The prognostic impact of O ⁶-methylguanine DNA methyltransferase and epidermal growth factor receptor expressions on primary gliosarcoma: A clinicopathologic and immunohistochemical study of seven cases at a single institution

Context: Gliosarcoma is an uncommon variant of glioblastoma characterized by a biphasic tissue pattern of glial and mesenchymal differentiation. O ⁶-methylguanine DNA methyltransferase (MGMT) is a DNA repair protein that removes mutagenic and cytotoxic adducts from O ⁶-guanine in DNA. Lack of MGMT protein expression immunohistochemically is related to drug responses in patients of malignant glioma treated with alkylating agents. Epidermal growth factor receptor (EGFR) is the most frequently amplified gene in glioblastoma and associated with tumor invasiveness, angiogenesis, poor survival, and resistance to radiation therapy. Aims: To elucidate the relationship between the statuses of the MGMT as well as EGFR proteins and the prognosis. The study was undertaken on samples received at the Department of Pathology from 2003 to 2009. Materials and Methods: Clinicopathologic and immunohistochemical study of seven cases was performed. Results: This series included three men and four women with a mean age of 49.3 years at first surgery. The median progression-free survival (PFS) was 22.2 months and 8.6 months for primary tumors with 0 to 1+ and 2+ to 3+ MGMT staining, respectively; the median overall survival (OS) was 27.5 months and 14.2 months for primary tumors with 0 to 1+ and 2+ to 3+ MGMT staining, respectively. The median PFS was 17.2 months and 11.2 months for primary tumors with 0 to 1+ and 2+ to 3+ EGFR staining, respectively; the median OS was 20.4 months and 17.7 months for primary tumors with 0 to 1+ and 2+ to 3+ EGFR staining, respectively. Conclusions: The series showed that MGMT and EGFR protein expressions were both unfavorable prognostic factors for patients with gliosarcoma.