Table 2.

Summary ORs and 95% CI of MTHFR C677T polymorphism and lung cancer risk.

Analysis model	Ethnicity	OR	95% CI (P value)	Pa
T vs. C	Overall	1.15b	0.97–1.37 (0.109)	0.000
	Han	1.20b	0.65–2.22 (0.566)	0.000
	Not stated	1.18b	0.95–1.47 (0.143)	0.002
TT vs. CC	Overall	1.35b	0.99–1.83 (0.058)	0.002
	Han	1.43b	0.77–2.67 (0.259)	0.004
	Not stated	1.42	1.02–1.97 (0.036)	0.076
TT + CT vs. CC	Overall	1.18b	0.91–1.53 (0.205)	0.000
	Han	1.10b	073–1.65 (0.648)	0.021
	Not stated	1.35b	0.92–1.98 (0.128)	0.000
TT vs. CC + CT	Overall	1.25b	0.99–1.57 (0.060)	0.014
	Han	1.47b	0.87–2.47 (0.148)	0.005
	Not stated	1.22	1.03–1.44 (0.021)	0.212
Source of controls
Population-based
T vs. C	–	1.12b	0.93–1.33 (0.225)	0.001
TT vs. CC	–	1.37	1.14–1.65 (0.001)	0.063
TT + CT vs. CC	–	1.14b	0.86–1.52 (0.349)	0.000
TT vs. CC + CT	–	1.25	1.07–1.45 (0.004)	0.070
Hospital-based
T vs. C	–	1.45b	0.60–3.50 (0.414)	0.000
TT vs. CC	–	0.49b	0.09–2.66 (0.412)	0.001
TT + CT vs. CC	–	1.53b	0.48–4.86 (0.475)	0.002
TT vs. CC + CT	–	1.65b	0.53–5.09 (0.384)	0.006
Subgroup by area
South China*
T vs. C	–	1.09b	0.86–1.39 (0.481)	0.000
TT vs. CC	–	1.20b	0.77–1.89 (0.422)	0.007
TT + CT vs. CC	–	1.13b	0.81–1.57 (0.487)	0.000
TT vs. CC + CT	–	1.06	0.87–1.30 (0.552)	0.115
North China**
T vs. C	–	1.28	1.14–1.44 (0.000)	0.293
TT vs. CC	–	1.67	1.33–2.10 (0.000)	0.615
TT + CT vs. CC	–	1.39	1.15–1.69 (0.001)	0.178
TT vs. CC + CT	–	1.46b	1.03–2.06 (0.034)	0.031

^aP value for heterogeneity;

^bEstimates for random effects model.

^*South China including Taiwan, Yunnan, Guangzhou, Nanjing, Hubei and Jiangxi;

^**North China including Beijing, Shandong and Henan.