Table 2.

Relative risks of breast cancer in Generations Study members by family history score (FHS), adjusted for other breast cancer risk factors^*

Family History Score	No. of study participants	Person-years (1000)	No. of breast cancer cases	HR	95% CI	P
0a	88,219	534.5	1,301	1.00	baseline
<10	3610	21.7	126	1.61	1.34, 1.94	<0.0001
10–<20	4563	27.5	134	1.63	1.36, 1.95	<0.0001
20–< 50	4334	26.2	94	1.72	1.39, 2.12	<0.0001
50–< 100	1692	10.2	37	2.11	1.52, 2.92	<0.0001
≥100	1320	7.9	41	3.50	2.56, 4.79	<0.0001
Total	103,738	627.9	1,733	Test for trendb: <0.0001

HR Hazard Ratio from Cox regression using age as time scale, CI Confidence interval

^*Adjusted for age at menarche, benign breast disease, oral contraceptive use, parity, age at first birth, breastfeeding, age at menopause, hormone replacement therapy use, physical activity, pre- and post-menopausal body mass index, alcohol intake, smoking status, and socioeconomic status

^aNo history of breast cancer in first-degree female relatives

^bTest for trend across six groups scored 0–5