Table 3.

Median Survival according to EGFR IHC Status

WHO group	Median survival by EGFR IHC (years)				Overall P	P values between EGFR IHC subgroups
	Neg	Weak	Mod	Strong		Neg vs weak	Neg vs mod	Neg vs strong	Weak vs mod	Weak vs strong	Mod vs strong
All gliomas	Undefined	1.6	1.9	0.99	<0.0001⁎	0.029	0.058	0.0003⁎	0.50	0.0032⁎	<0.0001⁎
Astrocytoma
Grade II	Undefined	Undefined	6.37	Undefined	0.32	0.25	0.21	0.14	0.45	0.25	0.40
Grade III	Undefined	1.9	2.5	1.7	0.54	0.33	0.41	0.33	0.36	0.88	0.29
GBM	1.2	0.68	0.57	0.80	0.097	0.23	0.12	0.39	0.43	0.36	0.025⁎
Oligodendroglioma
Grade II	Undefined	Undefined	Undefined	4.3	0.02⁎	0.37	0.40	0.050⁎	0.71	0.084	0.013⁎
Grade III	NA	1.1	Undefined	2.7	0.03⁎	NA	NA	NA	0.025⁎	0.016⁎	0.79

A total of 750 diffusely infiltrative astrocytomas and oligodendrogliomas, WHO grades II to IV, were prospectively analyzed for EGFR expression via IHC semiquantification (see Materials and Methods). Median survival after diagnosis was determined by Kaplan-Meier curves, with statistical significance calculated via log-rank tests.

mod, moderate; NA, not available (no grade III oligodendrogliomas were immunonegative for EGFR); neg, negative.

^⁎Significant correlations.