Breast Cancer

Epidemiology

  • In U.S., most common cancer in women; 2nd leading cause of cancer death in women
  • Genetic risk: 15–20% ⊕ FHx → 2× ↑ risk; ~45% familial cases a/w germline mutation
    • BRCA1/2: 35–85% lifetime risk of breast ca & ↑ risk of ovarian & prostate ca; ? ↑ colon ca; BRCA2: ↑ male breast, prostate & pancreatic ca. Germline loss-of-function mutations in PALB2 a/w 35% ↑ risk breast cancer by age 70 (NEJM 2014;371:497).
  • Estrogen: ↑ risk with early menarche, late menopause, late parity or nulliparity (NEJM 2006;354:270); prolonged HRT (RR = 1.24 after 5.6 y;