Increased 5-hydroxymethylcytosine is a favorable prognostic factor of Helicobacter pylori-negative gastric cancer patients

Table 1 5-hydroxymethylcytosine levels between different characteristics, n = 144

Characteristics	Total, n (%)	5-hmC low, n (%)	5-hmC high, n (%)	P value
Sex
Male	45 (31.3)	17 (24.3)	28 (37.8)	0.079
Female	99 (68.7)	53 (75.7)	46 (62.2)
Age in yr
< 60	56 (38.9)	35 (50.0)	21 (28.4)	0.008
≥ 60	88 (61.1)	35 (50.0)	53 (71.6)
Histological grade
Low	106 (73.6)	47 (67.1)	59 (79.7)	0.087
High	38 (26.4)	23 (32.9)	15 (20.3)
WHO Classification
Tubular adenocarcinoma	115 (79.9)	55 (78.6)	60 (81.1)	0.707
Others	29 (20.1)	15 (21.4)	14 (18.9)
Tumor size in cm
< 5	62 (43.1)	32 (45.7)	30 (40.5)	0.531
≥ 5	82 (56.9)	38 (54.3)	44 (59.5)
Vascular invasion
Negative	39 (27.1)	23 (32.9)	16 (21.6)	0.129
Positive	105 (72.9)	47 (67.1)	58 (78.4)
Neural invasion
Negative	64 (44.4)	39 (55.7)	25 (33.8)	0.008
Positive	80 (55.6)	31 (44.3)	49 (66.2)
Depth of invasion
T1/T2	54 (37.5)	30 (42.9)	24 (32.4)	0.197
T3/T4	90 (62.5)	40 (57.1)	50 (67.6)
Lymph metastasis
N0	41 (28.5)	24 (34.3)	17 (23.0)	0.133
N1/N2/N3	103 (71.5)	46 (65.7)	57 (77.0)
TNM stage
Ⅰ + Ⅱ	73 (50.7)	43 (61.4)	30 (40.5)	0.012
Ⅲ	71 (49.3)	27 (38.6)	44 (59.5)
Chemotherapy
No	75 (52.1)	33 (47.1)	42 (56.8)	0.248
Yes	69 (47.9)	37 (52.9)	32 (43.2)
H. pylori
Negative	55 (38.2)	21 (30.0)	34 (45.9)	0.049
Positive	89 (61.8)	49 (70.0)	40 (54.1)

5-hmC: 5-hydroxymethylcytosine; H. pylori: Helicobacter pylori; WHO: World Health Organization.

Table 2 5-hydroxymethylcytosine level stratified by different characteristics according to Helicobacter pylori infection condition

Characteristics	H. pylori (-), n = 55		H. pylori (+), n = 89
	5-hmC high, n (%)	P value	5-hmC high, n (%)	P value
Sex
Male	18 (50.0)	0.013	28 (44.4)	0.883
Female	16 (84.2)		12 (46.2)
Age in yr
< 60	10 (55.6)	0.505	11 (28.9)	0.009
≥ 60	24 (64.9)		29 (56.9)
Histological grade
High	10 (55.6)	0.505	5 (25.0)	0.042
Low	24 (64.9)		35 (50.7)
WHO classification
Tubular adenocarcinoma	31 (60.8)	11	29 (45.3)	0.911
Others	3 (75.0)		11 (44.0)
Tumor size in cm
< 5	13 (61.9)	0.992	17 (41.5)	0.542
≥ 5	21 (61.8)		23 (47.9)
Vascular invasion
Negative	10 (52.6)	0.308	6 (30.0)	0.127
Positive	24 (66.7)		34 (49.3)
Neural invasion
Negative	16 (57.1)	0.467	9 (25.0)	0.002
Positive	18 (66.7)		31 (58.5)
Depth of invasion
T1/T2	12 (50.0)	0.112	12 (40.0)	0.504
T3/T4	22 (71.0)		28 (47.5)
Lymph metastasis
N0	9 (50.0)	0.208	8 (34.8)	0.255
N1/N2/N3	25 (67.6)		32 (48.5)
TNM stage
Ⅰ + Ⅱ	17 (54.8)	0.226	13 (31.0)	0.012
Ⅲ	17 (70.8)		27 (57.4)
Chemotherapy
No	19 (61.3)	0.927	23 (52.3)	0.169
Yes	15 (62.5)		17 (37.8)

¹P value of Fisher’ exact test. 5-hmC: 5-hydroxymethylcytosine; H. pylori: Helicobacter pylori; WHO: World Health Organization.

Table 3 Multivariate analyses of risk factors affecting overall survival in total patients, n = 144

Characteristics		HR (95%CI)	P value
Tumor size in cm	< 5	1	0.027
	≥ 5	1.78 (1.07-2.95)
Histological grade	High	1	0.011
	Low	2.25 (1.21-4.18)
TNM stage	Ⅰ + Ⅱ	1	< 0.001
	Ⅲ	2.84 (1.72-4.70)
5-hmC	Low	1	0.040
	High	0.61 (0.38-0.98)

5-hmC: 5-hydroxymethylcytosine; CI: Confidence interval; HR: Hazard ratio.

Table 4 Multivariate analysis of risk factors affecting overall survival in the Helicobacter pylori-negative subgroup, n = 55

Characteristics		HR (95%CI)	P value
Neural invasion	Negative	1	< 0.001
	Positive	5.45 (2.28-13.07)
Tumor size in cm	< 5	1	0.031
	≥ 5	2.63 (1.09-6.32)
5-hmC	Low	1	0.004
	High	0.30 (0.13-0.68)

5-hmC: 5-hydroxymethylcytosine; CI: Confidence interval; HR: Hazard ratio.

Table 5 Multivariate analyses of risk factors affecting overall survival in the TNM stage I + II subgroup, n = 73

Characteristics		HR (95%CI)	P value
Sex	Female	1	0.047
	Male	0.43 (0.19-0.99)
5-hmC	Low	1	0.011
	High	0.32 (0.13-0.77)

5-hmC: 5-hydroxymethylcytosine; CI: Confidence interval; HR: Hazard ratio.