. 2012 Dec 6;177(2):161–170. doi: 10.1093/aje/kws238

Table 3.

Interaction Analyses of Genetic Risk Score and Breast Cancer Risk Factors Among 6,408 Chinese Women, the Shanghai Breast Cancer Genetics Study, 1996–1998 and 2002–2005

Characteristic or Risk Factor	Genetic Risk Score^a
	Continuous			By Tertiles
	OR^b	95% CI	P value^c	<7.3		7.3–9.7		>9.7		P value^c
	OR^b	95% CI	P value^c	OR^b	95% CI	OR^b	95% CI	OR^b	95% CI	P value^c
All women	1.13*	1.11, 1.14	8.01 × 10⁻²⁹*	1.00	Referent	1.38*	1.21, 1.56	1.89*	1.68, 2.14	4.65 × 10⁻²⁵*
Age at menarche, years
>13	1.10*	1.08, 1.12	0.743	1.00	Referent	1.35*	1.16, 1.58	1.90*	1.64, 2.20	0.893
≤13	1.11*	1.07, 1.14		1.23*	1.00, 1.50	1.77*	1.45, 2.14	2.30*	1.92, 2.77
Age at menopause, years^d
≤50	1.09*	1.06, 1.13	0.768	1.00	Referent	1.11	0.88, 1.41	1.55*	1.24, 1.93	0.343
>50	1.10*	1.05, 1.15		1.03	0.76, 1.39	1.34	1.00, 1.79	1.93*	1.44, 2.57
Years of menstruation
30	1.09*	1.06, 1.12	0.194	1.00	Referent	1.35*	1.10, 1.65	1.77*	1.45, 2.15	0.301
>30	1.11*	1.09, 1.14		1.16	0.95, 1.41	1.63*	1.35, 1.99	2.30*	1.91, 2.78
Parity/age at first live birth, years
≤25	1.12*	1.09, 1.15	0.570	1.00	Referent	1.12	0.92, 1.37	1.79*	1.48, 2.17	0.644
>25 or nulliparous	1.11*	1.08, 1.13		1.12	0.93, 1.35	1.76*	1.46, 2.11	2.19*	1.83, 2.62
Total breastfeeding, months
>12 total	1.10*	1.06, 1.13	0.621	1.00	Referent	1.18	0.91, 1.51	1.73*	1.36, 2.21	0.456
≤12	1.11*	1.08, 1.13		1.18	0.94, 1.47	1.72*	1.37, 2.15	2.31*	1.85, 2.87
Family history of breast cancer
No	1.10*	1.08, 1.12	0.897	1.00	Referent	1.33*	1.16, 1.52	1.86*	1.64, 2.11	0.811
Yes	1.10*	1.01, 1.21		2.02*	1.18, 3.48	1.65*	1.02, 2.68	3.29*	2.13, 5.07
History of benign breast disease
No	1.09*	1.07, 1.12	0.789	1.00	Referent	1.28*	1.08, 1.51	1.80*	1.53, 2.10	0.824
Yes	1.11*	1.07, 1.13		1.66*	1.36, 2.02	2.22*	1.84, 2.70	3.09*	2.59, 3.70
Hormone replacement therapy
No	1.10*	1.08, 1.12	0.836	1.00	Referent	1.38*	1.22, 1.57	1.91*	1.68, 2.16	0.401
Yes	1.10	1.00, 1.21		1.53	0.92, 2.56	1.76*	1.07, 2.89	2.24*	1.47, 3.43
Body mass index^e
≤25	1.10*	1.08, 1.13	0.735	1.00	Referent	1.49*	1.28, 1.73	1.86*	1.61, 2.15	0.303
>25	1.11*	1.07, 1.14		1.36*	1.11, 1.66	1.58*	1.30, 1.93	2.81*	2.32, 3.40
Waist/hip ratio
≤0.81	1.11*	1.08, 1.14	0.779	1.00	Referent	1.49*	1.23, 1.80	2.00*	1.66, 2.40	0.570
>0.81	1.10*	1.08, 1.13		1.75*	1.45, 2.11	2.33*	1.93, 2.81	3.24*	2.70, 3.89
Regular physical activity^f
Yes	1.11*	1.08, 1.13	0.990	1.00	Referent	1.00	0.77, 1.28	1.76*	1.39, 2.22	0.682
No	1.10*	1.08, 1.12		1.17	0.95, 1.45	1.70*	1.37, 2.09	2.24*	1.82, 2.74

Abbreviations: CI, confidence interval; OR, odds ratio.

* P ≤ 0.05 (significant).

^a Genetic risk score based on genotypes for rs4973768, rs10941679, rs889312, rs2046210, rs13281615, rs704010, rs1219648, rs3817198, rs3803662, and rs4784227.

^b Derived from logistic regression, adjusted for age and education.

^c P value for association or trend for genetic risk score among all women; P values for interaction in stratified analyses.

^d Among postmenopausal women.

^e Body mass index: weight (kg)/height (m)².

^f Among women from case-control studies.