What are the risk factors for breast cancer?

Although not yet know exactly what causes breast cancer, we do know that certain risk factors associated with the disease. A risk factor is anything that increases the likelihood that a person will develop a disease such as cancer. Different cancers have different risk factors. Some risk factors, such as smoking, alcohol and diet are linked to things a person does. Others, such as the person's age, race or family history, can not be changed.

But risk factors do not tell us everything. Having a risk factor, or even several, does not mean that a woman will get breast cancer. Some women who have one or more risk factors never develop the disease, and most women who have it do not have any risk factors (other than being a woman and getting older). Some factors weigh more heavily on the risk than others, and your risk of breast cancer may change over time due to aging or to changes in lifestyle.

Although many risk factors may increase the chances of reaching for breast cancer it is not yet known exactly how some of these risk factors cause cells to become cancerous. Hormones seem to play a role in many cases of breast cancer, but we do not know fully how this happens.

Risk factors you can not change

Incidence by sex: breast cancer is much more common in women than in men.

Age: risk increases with age.

Genetic risk factors: hereditary changes (mutations) in certain genes, such as BRCA1 and BRCA2, may increase the risk.

Family history: Breast cancer risk is higher among women whose close blood relatives developed the disease.

Personal history of breast cancer: A woman with cancer in one breast has a greater chance of developing another breast cancer (ie other than the return of the first cancer).

Race: In general, white women are more likely to get breast cancer than women slightly black. The black women are more likely to die from this cancer.

Dense breast tissue: Dense breast tissue means there is more glandular tissue and less fatty tissue. Women with denser breast tissue have a higher risk of breast cancer.
Certain problems benign (not cancer) within: women with certain benign breast changes may be at increased risk of developing breast cancer. Some of these changes are more linked to risk of breast cancer than others. For more information, see our document, Non-cancerous Breast Conditions.

Lobular carcinoma in situ: in this condition, cells that look like cancer cells are found in the milk-producing glands (lobules), but these do not grow through the wall of the lobules, and can not spread to other parts of body. This is not a true cancer or precancer, but LCIS (lobular carcinoma in situ carcinoma LCIS) increases the risk that a woman will develop cancer in either breast later.

Periods: Women who began menstruating at an early age (before age 12) or went through menopause (stopped having menstrual periods) after age 55 have a slightly higher risk for breast cancer.

Breast radiation early in life: women who received radiation treatment to the chest area (chest), as part of their treatment for another cancer during their childhood or as young adults, have a significantly higher risk of breast cancer .

Treatment with DES: women who were given the drug DES (diethylstilbestrol) during pregnancy have a slightly higher risk of developing breast cancer. For more information, consult our document (available in English) DES Exposure: Questions and Answers.

Risk of breast cancer and decisions lifestyle

Not having children or having them at a later age in life: Women who have not had children or those who had their first child after age 30 have a slightly higher risk of developing breast cancer. Having been pregnant many times or pregnant at a younger age reduces the risk of breast cancer.

Certain types of contraceptives: studies have reported that women using birth control pills or an injectable form of contraception called medroxyprogesterone acetate (DMPA or Depo-Provera) have a slightly higher risk of breast cancer than women that have never been used. The risk appears lower than normal over time once they stop taking birth control pills.
Hormone therapy after menopause taking estrogen and progesterone after menopause (sometimes called combined hormone therapy) increases the risk of breast cancer. The risk appears lower than normal over time once the hormones are stopped. For more information on this topic, see our Menopausal Hormone Therapy.
Not breastfeed their babies: some studies suggest that breastfeeding slightly lowers the risk of breast cancer, especially if breastfeeding is 1½ to 2 years.

Alcohol: The consumption of alcohol is clearly associated with an increased risk of developing breast cancer. Even as little as one drink a day can increase the risk.

Overweight and obesity: being overweight or obese after menopause (or because the weight gain took place during adulthood) is associated with an increased risk of breast cancer.

Source: http://www.cancer.org/