BREAST CANCER
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Descriptive Epidemiology
See chapter 7.10 page 289 in WCRF/AICR Food, Nutrition, Physical Activity, and the Prevention of Cancer: a Global Perspective.
1.15 million new cases in 2002, most common cancer in women.
Incidence and mortality from this cancer is in general increasing throughout the world, especially in the developed world.
High risk areas: North America and Europe (400,000 cases in 1996), lowest rates in Asia and Africa.
Some of the increase due to screening?
5-year survival rates are 50% with appropriate treatment.
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Pathogenesis
Clearest risk factors for breast cancer are hormonal and reproductive risk factors.
Role of hormones:
- Increase cell proliferation, increase the risk of somatic mutations
- May also have promoting effect – stimulate mitotic division of initiated cells
Non-dietary risk factors for breast cancer
- Early age at menarche (first menstrual period)
- Nulliparity (no children)
- Late age at first birth
- Late natural menopause
- (All these factors increase reproductive life time – and total exposure to luteal phase levels of estrogens and progesterone)
Protective factor:
- breastfeeding
Other causes:
- Postmenopausal combined estrogen and progestin therapy
- Family history in a first degree relative (mother or sister)
- BRCA1/BRCA2, ATM mutations (rare)
- NOTE: High mammographic density
Dietary risk factors for breast cancer
CONVINCING EVIDENCE - decreases risk:
- Lactation
CONVINCING EVIDENCE - increases risk:
- Alcoholic drinks
- Body fatness AFTER menopause
PROBABLE EVIDENCE - decreases risk:
- Body fatness BEFORE menopause
PROBABLE EVIDENCE - increases risk:
- Abdominal fatness
- Adult weight gain
LIMITED/SUGGESTIVE EVIDENCE - decreases risk:
None
LIMITED/SUGGESTIVE EVIDENCE - increases risk:
Total fat
Most effective dietary means of preventing breast cancer
- Maintenance of body weight by consumption or appropriate diets and by regular physical activity throughout life
- Avoidance of alcohol
Possibly:
- protective effect of vegetables and fruits