Assessment of Epidermal Growth Factor Receptor (EGFR) expression in human meningioma

Purpose: This study explores whether meningioma expresses epidermal
growth factor receptor (EGFR) and determines if there is a
correlation between the WHO grade of this tumor and the degree of
EGFR expression. Methods: Following institutional review board
approval, 113 meningioma specimens from 89 patients were chosen. Of
these, 85 were used for final analysis. After a blinded review,
immunohistochemical stains for EGFR were performed. Staining
intensity (SI) was scored on a scale 0-3 (from no staining to
strong staining). Staining percentage of immunoreactive cells (SP)
was scored 1-5 (from the least to the maximum percent of the
specimen staining). Immunohistochemical score (IHS) was calculated
as the product of SI and SP. Results: Eighty-five samples of
meningioma were classified in accordance with World Health
Organization (WHO) criteria: benign 57/85 (67%), atypical 23/85
(27%), and malignant 5/85 (6%). The majority of samples
demonstrated a moderate SI for EGFR. IHS for EGFR demonstrated a
significant association between SI and histopathologic subtype.
Also, there was a correlation between the SP and histopathologic
subtype (p = 0.029). A significant association was determined when
the benign and the atypical samples were compared to the malignant
with respect to the SP (p = 0.009). While there was a range of the
IHS for the benign and the atypical histologic subtypes, malignant
tumors exhibited the lowest score and were statistically different
from the benign and the atypical specimens (p < 0.001).
Conclusions: To our knowledge, this represents the largest series
of meningioma samples analyzed for EGFR expression reported in the
literature. EGFR expression is greatest in benign meningiomas and
may serve a potential target for therapeutic intervention with
selective EGFR inhibitors.