Know Your Risk
Most Women Underestimate Risk for Breast Cancer. Know the facts.
A risk factor is anything that affects your chance of getting a disease, such as cancer. Different cancers have different risk factors. For example, exposing skin to strong sunlight is a risk factor for skin cancer.
Smoking is a risk factor for cancers of the lung, mouth, larynx (voice box), bladder, kidney and several other organs.
But risk factors don’t tell us everything.
Having a risk factor, or even several, does not mean that you will get the disease. Most women who have one or more breast cancer risk factors never develop the disease, while many women with breast cancer have no apparent risk factors (other than being a woman and growing older). Even when a woman with risk factors develops breast cancer, it is hard to know just how much these factors might have contributed.
There are different kinds of risk factors.
Some factors, like a person’s age or race, can’t be changed. Others are linked to cancer-causing factors in the environment. Still others are related to personal behaviors, such as smoking, drinking and diet.
Some factors influence risk more than others, and your risk for breast cancer can change over time, due to factors such as aging or lifestyle.
RISK FACTORS YOU CANNOT CHANGE
Simply being a woman is the main risk factor for developing breast cancer. Men can develop breast cancer, but this disease is about 100 times more common among women than men. This is likely because men have less of the female hormones estrogen and progesterone, which can promote breast cancer cell growth.
Your risk of developing breast cancer increases as you get older. About 1 out of 8 invasive breast cancers are found in women younger than 45, while about 2 of 3 invasive breast cancers are found in women 55 or older.
Genetic risk factors
About 5 to 10 percent of breast cancer cases are thought to be hereditary, resulting directly from gene defects (called mutations) inherited from a parent.
BRCA1 and BRCA2: The most common cause of hereditary breast cancer is an inherited mutation in the BRCA1 and BRCA2 genes. In normal cells, these genes help prevent cancer by making proteins that keep the cells from growing abnormally. If you have inherited a mutated copy of either gene from a parent, you have a high risk of developing breast cancer during your lifetime. The risk may be as high as 80 percent for members of some families with BRCA mutations. These cancers tend to occur in younger women and more often affect both breasts than cancers in women who are not born with one of these gene mutations. Women with these inherited mutations also have an increased risk for developing other cancers, particularly ovarian cancer.
In the United States, BRCA mutations are more common in Jewish women of Ashkenazi (Eastern Europe) origin than in other racial and ethnic groups, but they can occur in any racial or ethnic group.
Changes In Other Genes: Other gene mutations can also lead to inherited breast cancers. These gene mutations are much rarer and often do not increase the risk of breast cancer as much as the BRCA genes. They are not frequent causes of inherited breast cancer.
Genetic Testing: Genetic tests can be done to look for mutations in the BRCA1 and BRCA2 genes (or some other genes linked to breast cancer risk). Although testing may be helpful in some situations, the pros and cons need to be considered carefully.
Family History Of Breast Cancer
Breast cancer risk is higher among women whose close blood relatives have this disease.
Having one first-degree relative (mother, sister, or daughter) with breast cancer approximately doubles a woman’s risk. Having two first-degree relatives increases her risk about three-fold.
The exact risk is not known, but women with a family history of breast cancer in a father or brother also have an increased risk of breast cancer. Altogether, less than 15 percent of women with breast cancer have a family member with this disease. This means that most women who get breast cancer (over 85 percent) do not have a family history of this disease.
Personal History Of Breast Cancer
A woman with cancer in one breast has a three- to four-fold increased risk of developing a new cancer in the other breast or in another part of the same breast. This is different from a recurrence (return) of the first cancer.
Race and Ethnicity
Overall, white women are slightly more likely to develop breast cancer than are African-American women, but African-American women are more likely to die of breast cancer. However, in women under 45, breast cancer is more common in African-American women. Asian, Hispanic and Native-American women have a lower risk of developing and dying from breast cancer.
Dense Breast Tissue
Breasts are made up of fatty tissue, fibrous tissue and glandular tissue. Someone is said to have dense breast tissue (as seen on a mammogram) when they have more glandular and fibrous tissue and less fatty tissue. Women with dense breasts have a higher risk of breast cancer than women with less dense breasts. Unfortunately, dense breast tissue can also make mammograms less accurate.
A number of factors can affect breast density, such as age, menopausal status, including the use of drugs (such as menopausal hormone therapy), pregnancy and genetics.
Women who have had more menstrual cycles because they started menstruating early (before age 12) and/or went through menopause later (after age 55) have a slightly higher risk of breast cancer. The increase in risk may be due to a longer lifetime exposure to the hormones estrogen and progesterone.
Previous Chest Radiation
Women who as children or young adults had radiation therapy to the chest area as treatment for another cancer (such as Hodgkin disease or non-Hodgkin lymphoma) have a significantly increased risk for breast cancer. This varies with the patient’s age when they had radiation. If chemotherapy was also given, it may have stopped ovarian hormone production for some time, lowering the risk. The risk of developing breast cancer from chest radiation is highest if the radiation was given during adolescence, when the breasts were still developing. Radiation treatment after age 40 does not seem to increase breast cancer risk.