A case-control study of the HER2 Ile655Val polymorphism in relation to risk of invasive breast cancer

Breast Cancer Research

Table 3 Risk of invasive breast cancer according to the HER2 Ile655Val polymorphism and common risk factors

Risk factor*	HER2 polymorphism
	Ile/Ile, cases/controls	Val/Val, cases/controls	Ile/Ile, OR^†, 95% CI	Val/Val, OR^† (95% CI)	P ^‡
Age (years)					0.29
<55	317/256	32/29	1 (reference)	0.78 (0.44–1.37)
55+	320/295	29/40	1 (reference)	0.51 (0.29–0.89)
Family history of breast cancer					0.24
None	505/461	41/59	1 (reference)	0.54 (0.35–0.84)
Any	128/79	19/10	1 (reference)	0.92 (0.32–2.62)
Age at menarche (years)					0.14
<13	288/249	32/35	1 (reference)	0.88 (0.50–1.54)
≥ 13	346/297	29/33	1 (reference)	0.47 (0.27–0.84)
HRT use^§					0.19
Never/former	149/169	12/10	1 (reference)	1.24 (0.46–3.39)
Current	212/163	18/23	1 (reference)	0.46 (0.22–0.97)
Recent body mass index^§					0.07
<25.3 kg/m²	159/166	14/10	1 (reference)	1.01 (0.39–2.64)
≥ 25.3 kg/m²	196/163	14/25	1 (reference)	0.43 (0.20–0.91)
Weight change since age 18 years (kg)^§					0.12
Lost 5 to gained 11	142/148	14/11	1 (reference)	1.04 (0.41–2.67)
Gained 12 or more	204/164	14/22	1 (reference)	0.44 (0.20–0.98)

*Risk factor cut-points based on the approximate median values for the controls; ^†logistic regression models conditional on age and, as appropriate, adjusted for family history of breast cancer, recent alcohol consumption, parity, menopausal status, age at menopause, hormone replacement therapy use, age at menarche, height at age 25 years, weight at age 18 years, and weight change since age 18 years; ^‡ P interaction using the likelihood ratio test and assuming a multiplicative model (risk factors parameterized as dichotomous variables as shown in the table for purposes of the interaction tests); ^§ postmenopausal women only. CI, confidence interval; HRT, hormone replacement therapy; OR, odds ratio.

ISSN: 1465-542X