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Breast Cancer Risk Factors

Any woman may develop breast cancer.  However, the following risk factors may increase the likelihood of developing the disease.

1. Risk factors that cannot be changed:
• Gender. Breast cancer occurs nearly 100 times more often in women than in men.
• Aging. A majority of cases occur after age 50.
• Personal history of breast cancer.
• Previous breast irradiation.
• Family history and genetic factors. Having a close relative, such as a mother or sister, with breast cancer increases the risk.
• Benign breast disease.
• Previous breast biopsy in which the tissue showed atypical hyperplasia.
• Menstrual periods that began early in life.
• Menopause began later in life.
2. The most frequently cited lifestyle-related risk factors:
• smoking
• not having children
• not breastfeeding
• oral contraceptives
• obesity and a high-fat diet
• physical inactivity
• alcohol
• estrogen replacement therapy
• induced abortion
• obesity after menopause 
3. Environmental risk factors:
• Exposure to pesticides, or other chemicals, is currently being examined as a possible risk factor.

About Breast Cancer Risk

Although there are some women who are at higher risk, the fact is all women are at risk for breast cancer. That's why it is so important to follow the three-step plan for breast health. Early detection of problems provides the greatest possibility of successful treatment.

Some people with one or more risk factors never develop a disease, such as cancer, while others develop cancer and have no known risk factors.

Although certain factors may suggest or define a person's possible risks, they do not necessarily cause the disease.

Different diseases, including cancers, have different risk-factor lists. When reading about risk factors for breast cancer, keep in mind that the word "risk" is used in different ways:

• Lifetime risk refers to the probability that a person, over the course of his or her lifetime, will be diagnosed or die from cancer. Over her lifetime, a woman in the United States has a 1 in 8 risk of developing breast cancer, and a 1 in 28 risk of dying from breast cancer.
• Relative risk is a measure of the strength of the relationship between risk factors and cancer. With respect to breast cancer, it compares the risk of developing breast cancer in women who have a certain trait or exposure to women who do not have the trait or exposure. For example, women who have a family history of breast cancer are about 100 percent more likely to develop breast cancer than women who do not have a family history.

Source: National Cancer Institute