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The greatest risk factor is age and being a woman.
- Women are more likely to develop breast cancer as they
get older
- The highest number of cases occur in women aged between
60 and 70. About 25% of cases of breast cancer occur in
women under 50 (based on statistics from the Australian
Institute of Health and Welfare)
- Most women who get breast cancer have no other known risk
factors other than the risk that comes with age. Experts
say risk doubles every 10 years
- Only one in 100 breast cancers occur in men
- Note that while there are things that people intuitively
believe you can do to reduce your risk, there are very few
conclusive studies on risk factors.
Having a family history of breast and ovarian cancer can
increase risk, sometimes significantly.
- Having one or more close relatives with breast or ovarian
cancer can indicate higher risk
- The age when relatives had breast cancer diagnosed is
important. Risk increases with diagnoses before 50 and more
so with diagnosis before 40
- Having relatives who have had cancer in both breast increases
risk
- Having had a relative with both ovarian and breast cancer
increases risk further
- Some women have the BRCA1 or BRCA2 gene which increases
cancer risk significantly
- Ashkenazi Jewish women have a higher risk of hereditary
breast cancer.
See familial breast
cancer
The more periods you have, the greater your risk. Having
babies early lowers your risk.
- Women who have their first baby after 30 are about twice
as likely to get breast cancer as those who have their first
child before the age of 20
- Women at highest risk are those who have a first baby
after 35
- Women who have no children at all also have an increased
risk
- Women who start their periods late and end them early
are at less risk. Women who have a natural menopause after
55 are nearly twice as likely to get breast cancer as those
who go through menopause at 45.
- Women who have both ovaries removed at 35 run less than
half the risk of others
- In African and other countries where women start families
earlier, have larger families and breastfeed for longer,
the incidence of breast cancer is significantly lower
Breastfeeding reduces your risk.
- There is evidence that breastfeeding reduces risk, particularly
if you breastfeed for three months or more.
Previous breast cancer, some breast conditions or other
cancers may increase risk.
- Cancer in one breast increases the risk of recurrence
in that breast or a new cancer in the other breast
- Other breast conditions such as typical hyperplasia, lobal
carcinoma in situ or ductal carcinoma in situ increase the
risk of breast cancer
- Previous ovarian cancer may increase the risk
- Pervious bowel cancer may increase breast cancer risk.
There is believed to be a connection in some types of breast
cancers.
Taking the pill may increase your risk.
- There is evidence that breastfeeding reduces risk, particularly
if you breastfeed for three months or more
- Most doctors agree any risk is probably slight
- The current view is that there is little or no increase
in risk among those using the pill in their 20's and 30's
or between pregnancies
- Those who take the pill when they are very young (under
20) or shortly before the menopause (45 and over) may be
at greatest risk
- The longer you take the pill, the greater the risk.
HRT may increase your risk.
- Prolonged use of HRT (10 -15 years) is thought to increase
risk of breast cancer.
Lifestyle may impact your risk.
- Regular exercise appears to reduce risk. In California
researchers found that women who did 4 hours or more exercise
a week halved their breast cancer risk
- There is a relationship between a woman's weight and breast
cancer. Increased weight around the time of menopause increases
risk. Those who are overweight have greater stores of body
fat which is belied to raise oestrogen and decrease progesterone
levels
- Western women or Asian women living a western lifestyle
are at greater risk. Women in China and Japan have up to
five times less risk than Australian women (Although breast
cancer rates are rising). Experts believe that Asian foods,
and particularly Japanese food contributes to their lower
incidence of breast cancer in their own country
- Some foods are believed to reduce the risk of breast cancer.
See diet
- There is no evidence that alcohol causes breast cancer.
However studies have shown that regular alcohol intake may
increase risk and that risk is likely to increase with intake.
Drinking alcohol when young is believed to have the greatest
impact.
Environmental factors may increase risk.
- Radiation increases breast cancer risk. Excessive chest
X-rays at a young age may have an impact. There are studies
being undertaken into the impact of electromagnetic fields
- It has been suggested that use of some pesticides (such
as lindane and DDT) may cause breast cancer. Studies are
still being undertaken
- Contamination of animal fats with pesticides may increase
cancer risk
- Other chemicals which mimic oestrogen may also contribute
to risk.
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