. Author manuscript; available in PMC: 2018 Jul 1.

Published in final edited form as: Med Clin North Am. 2017 Jul;101(4):725–741. doi: 10.1016/j.mcna.2017.03.005

Table 1.

Relative Risks of Developing Breast Cancer for Women Age 40–49

Risk Factor	Breast Cancer Risk Ratio (95% CI)
Two 1^st degree relatives with breast cancer	3.84 (2.37–6.22)
1^st degree relative with breast cancer at age <40	3.0 (1.8–4.9)
1^st degree relative with breast cancer at age <50	2.17 (1.86–2.53)
One 1^st degree relative with breast cancer	2.14 (1.92–2.38)
Extremely dense breasts on mammography	2.04 (1.84–2.26)
Prior benign breast biopsy	1.87 (1.64–2.13)
2^nd degree relative with breast cancer	1.7 (1.4–2.0)
Heterogeneously dense breasts on mammography	1.62 (1.51–1.75)
Current oral contraceptive use	1.30 (1.13–1.49)
Nulliparity	1.25 (1.08–1.46)
Age at first birth ≥ 30 years	1.20 (1.02–1.42)

Adapted from Nelson HD, Zakher B, Cantor A, et al. Risk factors for breast cancer for women age 40 to 49: a systematic review and meta-analysis. Ann Intern Med 2012; 156(9):635–48; with permission.