Table 33.2. Established risk factors for breast cancer

Table 33.2. Established risk factors for breast cancer.
Risk factor	Relative risk
Age (≥50 vs. <50 years old)	6.5
Family history of breast cancer
First-degree relative	1.4-13.6
Second-degree relative	1.5-1.8
Age at menarche (<12 vs. ≥14 years old)	1.2-1.5
Age at menopause (≥55 vs. <55 years old)	1.5-2.0
Age at first live birth (>30 vs. <20 years old)	1.3-2.2
Benign breast disease
Breast biopsy (any histologic finding)	1.5-1.8
Atypical hyperplasia	4.0-4.4
Hormone replacement therapy	1.0-1.5
Radiation	1.7-3.0
Source: Adapted from Armstrong et al. The New England Journal of Medicine. Massachusetts Medial Society, Boston, 2000;¹⁰ Harris et al. The New England Journal of Medicine. Massachusetts Medical Society, Boston, 1992,¹² with permission.