Promoter hypermethylation of the SFRP2 gene is a high-frequent alteration and tumor-specific epigenetic marker in human breast cancer

Table 2 Correlation analysis of SFRP2 promoter methylation with clinicopathological and immunohistochemical patient characteristics

	*SFRP2* promoter
Variable	n ^a	Unmethylated (%)	Methylated (%)	R ^b	P ^c
Total	199	34 (17)	165 (83)
*Clinicopathological factors*
Age at diagnosis
< 60 years	114	24 (21)	90 (79)	0.122	0.091
≥ 60 years	85	10 (12)	75 (88)
Tumor size^d
pT1	70	11 (16)	59 (84)	-0.013	1.000
pT2 – 4	114	19 (17)	95 (83)
Lymph node status^d
pN0	89	19 (21)	70 (79)	0.129	0.106
pN1 – 3	85	10 (12)	75 (88)
Histological grade
G1 – G2	109	13 (12)	96 (88)	-0.139	0.069
G3	76	17 (22)	59 (78)
Histological type
ductal	155	26 (17)	129 (83)	-0.057	0.434
lobular	24	1 (4)	23 (96)
other	14	5 (36)	9 (64)
*Immunohistochemistry*
Estrogen receptor
negative (IRS^e 0 – 2)	64	13 (20)	51 (80)	0.084	0.295
positive (IRS 3 – 12)	123	17 (14)	106 (86)
Progesterone receptor
negative (IRS^e 0 – 2)	70	14 (20)	56 (80)	0.083	0.304
positive (IRS 3 – 12)	117	16 (14)	101 (86)

^aOnly female patients with primary, unilateral, invasive breast cancer were included. ^bPearson's correlation coefficient. ^cFisher's exact test (two-sided). ^dAccording to UICC: TNM Classification of Malignant Tumours [38]. ^eIRS = immunoreactivity score [40]. Significant P-values marked in bold face.

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