[N-clex] Breast cancer risk factor

- age↑

- white

- family Hx(genetic factor : BRCA, BRCA2)

- early menarch(12세), late menopause(55세)

- pre. breast, uterine, ovarian Ca

- nulliparity(임신X), late 1st childbirth(30세↑)

- obesity, radiation, alcohol, smoking

- HRT(hormone replacement therapy), oral pill

- menopause

- DES(estrogen)

- densetissue breast