Table 2.

Association between DNA methylation and sex, age, and selected exogenous factors in the ESCC

VariablesnFrequency of hypermethylation (%)
Cancer tissue
Remote normal-appearing tissue
P16MGMThMLH1Any geneP16MGMThMLH1Any gene
Sex
    Male8171 (87.7)21 (25.9)3 (3.7)74 (91.4)28 (34.6)8 (9.9)031 (38.3)
    Female4439 (88.6)13 (29.5)1 (2.3)39 (88.6)18 (40.9)6 (13.6)023 (52.3)
P0.8720.6641.000*0.752*0.4830.561*0.131
Age (y)
    <604943 (87.8)12 (24.5)2 (4.1)45 (91.8)20 (40.8)8 (16.3)025 (51.0)
    60+7667 (88.2)22 (28.9)2 (2.6)68 (89.5)26 (34.2)6 (7.9)029 (38.2)
P0.9460.5850.645*0.763*0.4550.1440.156
Tobacco smoking
    Never6859 (86.8)20 (29.4)2 (2.9)61 (89.7)26 (38.2)8 (11.8)032 (47.1)
    Ever5751 (89.5)14 (24.6)2 (3.5)52 (91.2)20 (35.1)6 (10.5)022 (38.6)
P0.6430.5441.000*0.7740.7160.8270.341
Alcohol drinking
    Never7164 (90.1)21 (29.6)2 (2.8)65 (91.5)31 (43.7)8 (11.3)036 (50.7)
    Ever5446 (85.2)13 (24.1)2 (3.7)48 (88.9)15 (27.8)6 (11.1)018 (33.3)
P0.3980.4931.000*0.6170.0680.9780.052
Fruit folate intake
    Q13732 (86.5)8 (21.6)033 (89.2)12 (32.4)3 (8.1)014 (37.8)
    Q24541 (91.1)17 (37.8)043 (95.6)16 (35.6)8 (17.8)020 (44.4)
    Q32924 (82.8)4 (13.8)1 (3.5)24 (82.8)11 (37.9)1 (3.5)012 (41.4)
    Q499 (100)5 (55.6)2 (22.2)9 (100)3 (33.3)2 (22.2)04 (44.4)
P0.535*0.027*0.004*0.230*0.974*0.139*0.933*
  • * Fisher's exact test.

  • The cut point of fruit folate intake is quartile (μg/d): Q1, 0; Q2, 26.3; Q3, 99.5; and Q4, 311.1.