What is Breast Cancer?

Breast cancer is a cancer that develops in the breast cells, and it is the most common invasive cancer found in women worldwide. While breast cancer can occur in men, the vast majority of cases occur in women. If you have been diagnosed with breast cancer, this means that the cells in a certain area of the breast are multiplying uncontrollable, usually forming a tumor.

Ductal breast cancer, starting in the ducts that allow milk to flow to the nipple, is the most common. However, lobular cancers that begin in the breast milk glands can also be common. There are also other rarer forms of breast cancer and usually benefit from care from a specialist in that area. Learn more about the symptoms of breast cancer. 

Knowledge is the first step in learning about breast cancer prevention and how you can reduce your risk of contracting the disease.

What Are The Causes of Breast Cancer?

Knowledge is the first step in learning about breast cancer prevention and how you can reduce your risk of contracting the disease. According to the National Cancer Institute, the following may be risk factors for breast cancer:

Estrogen (endogenous)

Endogenous estrogen is a hormone made by the body. It helps the body develop and maintain female sex characteristics. Being exposed to estrogen over a long time may increase the risk of breast cancer. Estrogen levels are highest during the years a woman is menstruating.

Hormone replacement therapy/Hormone therapy

Hormones that are made outside the body, in a laboratory, are called exogenous hormones. Estrogen, progestin or both may be given to replace the estrogen no longer produced by the ovaries in postmenopausal women or women who have had their ovaries removed.

Exposure to Radiation

Radiation therapy to the chest for the treatment of cancers increases the risk of breast cancer, starting 10 years after treatment and lasting for a lifetime. The risk of developing breast cancer depends on the dose of radiation and the age at which it is given. The risk is highest if radiation treatment was used during puberty. For example, radiation therapy used to treat Hodgkin disease by age 16, especially radiation to the chest and neck, increases the risk of breast cancer.

Obesity

Obesity increases the risk of breast cancer in postmenopausal women who have not used hormone replacement therapy.

Alcohol

Drinking alcohol increases the risk of breast cancer. The level of risk rises as the amount of alcohol consumed rises.

Inherited Risk

Women who have inherited certain changes in the BRCA1 and BRCA2 genes have a higher risk of breast cancer, and the breast cancer may develop at a younger age.

How to Decrease Your Risk

Certain healthy habits or decisions can reduce your risks of developing breast cancer. However, since there is a genetic component to breast cancer, there is no known way to completely prevent breast cancer. These lifestyle habits may help mitigate your risks:

Exercise

Exercising four or more hours a week may decrease hormone levels and help lower breast cancer risk. The effect of exercise on breast cancer risk may be greatest in premenopausal women of normal or low weight. Care should be taken to exercise safely, because exercise carries the risk of injury to bones and muscles.

Estrogen (decreased exposure)

Decreasing the length of time a woman's breast tissue is exposed to estrogen may help prevent breast cancer.

Selective estrogen receptor modulators

Selective estrogen receptor modulators (SERMs) are drugs that act like estrogen on some tissues in the body  but block the effect of estrogen on other tissues. Tamoxifen is a SERM that belongs to the family of drugs called antiestrogens. Antiestrogens block the effects of the hormone estrogen in the body. Tamoxifen lowers the risk of breast cancer in women who are at high risk for the disease. This effect lasts for several years after drug treatment is stopped.

Raloxifene is another SERM that helps prevent breast cancer. In postmenopausal women with osteoporosis (decreased bone density), raloxifene lowers the risk of breast cancer for women at both high risk and low risk of developing the disease. It is not known if raloxifene would have the same effect in women who do not have osteoporosis. Like tamoxifen, raloxifene may increase the risk of blood clots, especially in the lungs and legs, but does not appear to increase the risk of endometrial cancer.

Aromatase inhibitors

Aromatase inhibitors lower the risk of new breast cancers in postmenopausal women with a history of breast cancer. In postmenopausal women, taking aromatase inhibitors decreases the amount of estrogen made by the body. Before menopause, estrogen is made by the ovaries and other tissues in a woman's body, including the brain, fat tissue and skin. After menopause, the ovaries stop making estrogen, but the other tissues do not. Aromatase inhibitors block the action of an enzyme called aromatase, which is used to make all of the body's estrogen. Possible harms from taking aromatase inhibitors include osteoporosis and effects on brain function (such as talking, learning, and memory).

Prophylactic mastectomy

Some women who have a high risk of breast cancer may choose to have a prophylactic mastectomy (the removal of both breasts when there are no signs of cancer). The risk of breast cancer is lowered in these women. However, it is very important to have a cancer risk assessment and counseling about all options for possible prevention before making this decision. In some women, prophylactic mastectomy may cause anxiety, depression and concerns about body image.

Prophylactic oophorectomy

Some women who have a high risk of breast cancer may choose to have a prophylactic oophorectomy (the removal of both ovaries when there are no signs of cancer). This decreases the amount of estrogen made by the body and lowers the risk of breast cancer.

However, it is very important to have a cancer risk assessment and counseling before making this decision. The sudden drop in estrogen levels may cause the onset of symptoms of menopause, including hot flashes, trouble sleeping, anxiety and depression. Long-term effects include decreased sex drive, vaginal dryness and decreased bone density. These symptoms vary greatly among women.

Fenretinide

Fenretinide is a type of vitamin A called a retinoid. When given to premenopausal women who have a history of breast cancer, fenretinide may lower the risk of forming a new breast cancer. Taken over time, fenretinide may cause night blindness and skin disorders. Women must avoid pregnancy while taking this drug because it could harm a developing fetus.

Source: National Cancer Institute