Monday, November 24, 2008

Factors Which Increase and Decrease

Breast Cancer Risk

Factors Which INCREASE Breast Cancer Risk

Factor Mechanism
Increases estrogen exposure by impairing liver function
Benign proliferative breast disease
Result of increased estrogen exposure
BRCA genes
Inherited defects in cancer defense genes
Cigarette smoking Benzopyrenes damage DNA
Contraceptive steroids (in pills, patches, vaginal rings, IUDs or injectable forms)
Increases estrogen exposure
Early menarche Increases estrogen exposure
Female sex Increased estrogen exposure
High socio-economic group Delayed childbearing
Higher education Delayed childbearing
Hormone replacement therapy (HRT)
Increases estrogen exposure
Increasing age
Premenopausal: Increases estrogen exposure
Postmenopausal: Impairs immune function

Induced abortion
Leaves increased number of immature breast lobules and increases risk of premature births
Increases estrogen exposure
Late childbirth (over 30 years old)
Increases exposure of Type 1 & 2 lobulesto estrogen before first birth; long susceptibility window
Late menopause Increases estrogen exposure
Nulliparity (never bearing children)
Maturity of breast lobules does not occur
Premature birth before 32 weeks
Leaves increased number of immature breast lobules
Increases estrogen exposure
Postmenopausal obesity Increases estrogen exposure
Radiation Damages DNA
2nd trimester miscarriage
Leaves increased number of immature breast lobules

Factors Which Decrease Breast Cancer Risk

Factor Mechanism
Breast feeding
Decreases estrogen by decreasing number of menstrual cycles and/or ovulation
Cruciferous vegetables (e.g., broccoli, Brussels sprouts or DIM supplements)
Indole-3-carbinol decreases estrogen exposure by causing estrogen to be changed to an inactive metabolite of estrogen
Early menopause
Decreases estrogen exposure
Decreases estrogen exposure
Having children (especially starting at a young age)
Decreases number of immature breast lobules
Late menarche Decreases estrogen exposure
Omega-3 fatty acids (e.g., olive, flax seed, walnut oils)
Oophorectomy (removal of ovaries before menopause)
Decreases estrogen production
Soy isoflavonoids (phytoestrogens)
May block estrogen receptors

Factors Which Have No Effect on Breast Cancer Risk

Factor Reason
Saturated fat
Saturated fat intake not related to obesity
Spontaneous abortions
(miscarriages) in the first trimester
No increased levels of estrogen as found in healthy pregnancies