Wednesday, October 6, 2010

Risk Factors

As part of study, the following modifiable factors were associated with a higher risk of breast cancer. Note however, that breast cancer can form in the absence of these risk factors.

* Being overweight or obese: Women over 50 who are obese are more at risk than women of the same age whose BMI indicates normal weight. According to Health Canada, even a small excess of weight (5 kg or 11 lbs or more) is associated with an increased risk of breast cancer, especially after the ménopause3.

* Lack of physical activity.

* The consumption of alcohol: More alcohol consumption, the greater the risk of breast cancer increases, regardless of the type of alcohol consumed. This has been observed in several epidemiological studies, with premenopausal women and women ménopausées4 5. To reduce the risk of cancer, Canadian Cancer Society advises women to limit their alcohol intake to less than 1 drink per day and men less than 2 drinks per day6.

* Taking estrogen: Some studies show that oral contraceptives (the pill) increases slightly the risk of breast cancer among women who use them for over 4 years. This risk is however no longer observable 10 years after stopping use of the contraceptive pill. Further studies on the subject have not established a link between the pill and breast cancer. However, carriers of a BRCA mutation decreases the risk of ovarian cancer by taking birth control pills.

Furthermore, hormone replacement therapy at menopause, which combines estrogen and progesterone, increases slightly the risk of breast cancer when taken for more than 5 years. Five years after stopping hormone therapy, this increased risk is hardly visible. In the case of use of HRT for less than 5 years, the risk of breast cancer is not changed. A report of the Society of Obstetricians and Gynaecologists of Canada specifies that "having ever used oral contraceptives does not increase risk of breast cancer associated with hormone therapy" 7.

* Exposure to chemical carcinogens: Being in contact with chemicals in the environment (organochlorine pesticides (DDT), parabens, etc..) Could contribute to the formation of breast cancer. The link between cause and effect is however very difficult to establish.

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