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What is Breast Cancer?

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Risk Factors

Breast Cancer and Female Hormones

Studies have shown that a woman’s risk of developing breast cancer is related to her exposure to the estrogen hormone. Factors that increase the duration and/or levels of exposure to these hormones, which stimulate cell growth, have been associated with an increase in breast cancer risk.

The production of estrogen hormone is related to the period of menstruation, time of menopause, first pregnancy age, and breastfeeding habit. By looking at these factors, we may come up with the protective factors that might reduce the risk of breast cancer.

Reducing Breast Cancer Risk

cartoon6Reproductive History

A woman who has given birth is less likely to develop breast cancer because they have a lower cumulative exposure to endogenous hormones than those who have never given birth. Compared to women who gave birth to their first child after 30, the breast cancer risk of those who gave birth before 20 is lowered by 50%.

Breastfeeding History

Breastfeeding helps protect against breast cancer because it reduces a woman’s estrogen levels, and thus her cumulative exposure to endogenous hormones; the longer a woman breastfeeds her children, the lower her risk of having breast cancer.


Women who do not regularly exercise have a higher risk of breast cancer. A research by the National Institutes of Health shows that 1.25 to 2.5 hours of strolling per week can help reduce breast cancer risk by 18%.


Adopting a healthy, balanced diet is key to good health. Consume foods high in fibre, less red meats, processed, preserved or smoked food. Avoiding food that is sugar loaded, has a high fat content, or is high in sodium can help reduce the risk of breast cancer.

Risk Factors

The exact cause of breast cancer is unknown. However, factors that are known to increase breast cancer risk include:


An increased number of menstrual cycles increase a woman’s cumulative exposure to endogenous hormones in her lifetime. Women who start their period very young (before 12), or stop later than usual (after 55) are more likely to develop breast cancer.


More than half of women diagnosed with cancer are over 50. There is however, an increasing trend of women being diagnosed at an earlier age, particularly during their late 30s or early 40s. All women should be breast aware.

Family History

Having a close relative (a mother, sister or daughter) who has been diagnosed with breast cancer can increase your own risk. A small number of women have an especially high risk of breast cancer because of faulty genes they have inherited. Faults in known high-risk breast cancer genes include BRCA1 and BRCA2.

Individual Health History

Individuals with high-risk breast cancer genes like BRCA1 and BRAC2, or with a past history of benign breast issues (such as atypical hyperplasia), non-invasive breast cancer, ovarian cancer, or endometrial cancer, are more likely to be at risk of breast cancer.


Those taking hormone replacement therapy, combined oral contraceptive pills, and menopause hormone replacement therapy could have a higher risk of breast cancer.


Regular consumption of large amounts of alcohol can slightly increase the risk of breast cancer.


Being overweight, especially after menopause, increases the risk of breast cancer. Menstruation in female is coordinated by estrogen and progesterone. However, after menopause, the ovaries will stop producing estrogen and progesterone, while estrogen will still be produced by fat. If fat accumulates in the body, the excessive level of estrogen might increase the risk of breast cancer.


Long-term exposure to radiation, or moderate to high levels of radiation exposure, increases the risk of breast cancer.

Please note that these risk factors will not always directly result in breast cancer and the cause of breast cancer for the majority of women remains unknown.