Breast: Risk Factors

Genetic & Hormonal/Reproductive Factors

• BRCA Mutation (Relative Risk: 15) – Strongest Risk Factor
• Nulliparity or Later Age of First Full-Term Pregnancy; > 35 Years (Relative Risk: 1.2-1.9)
• Early Menarche; < 12-15 Years (Relative Risk: 1.3)
• Late Menopause; > 55 Years (Relative Risk: 1.2-1.5)
• Hormone Replacement with Estrogen/Progesterone (Relative Risk: 1.2-1.3)

Personal Breast History

• Personal History of Carcinoma In-Situ; DCIS/LCIS (Relative Risk: 16.4-17.3)
• Personal History of Invasive Breast Cancer (Relative Risk: 6.8)
• Personal History of Proliferative Lesion with Atypia; ADH/ALH (Relative Risk: 5.3)
• Personal History of Proliferative Lesion without Atypia (Relative Risk: 1.9-2.5)
• Increased Breast Tissue Density; ≥ 75% of the Breast (Relative Risk: 4-5)

Family History of Breast Cancer

• First Degree Relative with Postmenopausal Breast Cancer (Relative Risk: 1.8)
• First Degree Relative with Premenopausal Breast Cancer (Relative Risk: 3.3)
• Second Degree Relative with Breast Cancer (Relative Risk: 1.5)
• Two First Degree Relatives with Breast Cancer (Relative Risk: 3.6)

Other Risk Factors

• Increasing Age > 65 Years (Relative Risk: 5.8)
• Obesity (Relative Risk: 1.2-1.9)
• Prior Radiation Exposure (Relative Risk: 1.6)
• Increased Bone Mineral Density (Relative Risk: 1.3-1.6)
• Alcohol Abuse; ≥ 2 Drinks Per Day (Relative Risk: 1.2)
• Tobacco Use (Relative Risk: 1.1)

Risk Models

• Gail Risk Model
• Tyrer-Cuzick Model (IBIS Tool)
• *See Breast: Risk Models