Interaction of methylenetetrahydrofolate reductase C677T, cytochrome P4502E1 polymorphism and environment factors in esophageal cancer in Kazakh population

Table 3 Interaction between MTHFR 677 and consumption of green vegetables, fresh fruits in EC

Consumption of vegetables and fruits	MTHFR 677 genotype	Case (n)	Control (n)	χ2	P	OR (95% CI)
Green vegetables1
Frequently	C/C	19	89	-	-	1.00
Occasionally or less	C/C	41	81	7.62	0.006	2.37 (1.27-4.42)
Frequently	C/T + T/T	23	37	8.85	0.003	2.91 (1.42-5.97)
Occasionally or less	C/T + T/T	37	33	24.50	0.000	5.25 (2.66-10.39)
Freshfruits2
Frequently	C/C	6	54	-	-	1.00
Occasionally or less	C/C	54	116	10.90	0.001	4.19 (1.70-10.34)
Frequently	C/T + T/T	7	17	4.81	0.028	3.71 (1.10-12.54)
Occasionally or less	C/T + T/T	53	53	26.76	0.000	9.00 (3.57-22.71)

SIA: Synergic index of addition; RERI: Relative excess risk of interaction; API: Attributable proportion of interaction. SIA¹ = 5.25/ (2.37 + 2.91 - 1.00) = 1.23, RERI¹ = 5.25 - (2.37 + 2.91) + 1 = 0.97,API¹ = [5.25 - (2.37 + 2.91) + 1]/5.25 = 18.48%; SIA² = 9.00/(4.19 + 3.71 - 1.00) = 1.30, RERI² = 9.00 - (4.19 + 3.71) + 1 = 2.10, API² = [9.00 - (4.19 + 3.71) + 1]/9.00 = 23.33%.