Epigenetic modulation of the drug resistance genes MGMT, ABCB1 and ABCG2 in glioblastoma multiforme

Table 5 Multivariate analysis of ABCB1 promoter methylation and its association with the overall survival of GBM patients

Variable	Haz. ratio	p-value	[95% Conf. Interval]
Sex
male	1.457	0.276	0.740	2.866
(ref. female)	1.130	0.793	0.454	2.813
(ref. female)	4.222	0.043	1.045	17.060
Age
50- < 60 years	1.793	0.282	0.619	5.191
(ref. <50 years)	1.500	0.490	0.474	4.742
(ref. <50 years)	5.358	0.234	0.338	84.863
Age
60- < 70 years	2.474	0.066	0.942	6.499
(ref. <50 years)	2.235	0.140	0.768	6.507
(ref. <50 years)	3.596	0.290	0.336	38.441
Age
≥70 years	6.069	0.001	2.107	17.479
(ref. <50 years)	9.872	0.000	2.786	34.988
(ref. <50 years)	5.112	0.167	0.505	51.721
Mean methylation level (continuous)
	0.995	0.461	0.981	1.009
	1.002	0.864	0.984	1.020
	0.973	0.032	0.950	0.998

Continuous multivariate Cox model regression analysis of ABCB1 promoter methylation and its association with the overall survival (OS) of the analyzed patients with glioblastoma multiforme, adjusted for potential risk factors including sex and age at diagnosis and stratified on the variable therapy. Normal typed data: the entire glioblastoma cohort; Italic data: Temozolomide treated glioblastoma patients; Bold face data: Glioblastoma patients without temozolomide treatment (Haz. Ratio, Hazard Ratio; Conf. Interval, Confidence Interval).