June 29th, 2012 by Hasham
What Are The Risk Factors For Breast Cancer?
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 may have contributed to her cancer.
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 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 age 55 or older.
Genetic risk factors
About 5% to 10% of breast cancer cases are thought to be hereditary, resulting directly from gene defects (called mutations) inherited from a parent. See the section, “Do we know what causes breast cancer?” for more information about genes and DNA.
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% 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 found most often in Jewish women of Ashkenazi (Eastern Europe) origin, but they can occur in any racial or ethnic group.
Breast Cancer Risk Factors
Every woman wants to know what she can do to lower her risk of breast cancer. Some of the factors associated with breast cancer — being a woman, your age, and your genetics, for example — can’t be changed. Other factors — maintaining a healthy weight, exercising, smoking cigarettes, and eating nutritious food — can be changed by making choices. By choosing the healthiest lifestyle options possible, you can empower yourself and make sure your breast cancer risk is as low as possible.
The known risk factors for breast cancer are listed below. Click on each link to learn more about the risk factor and ways you can minimize it in your own life. If a factor can’t be changed (such as your genetics), you can learn about protective steps you can take that can help keep your risk as low as possible.
Being a Woman
Just being a woman is the biggest risk factor for developing breast cancer. There are about 190,000 new cases of invasive breast cancer and 60,000 cases of non-invasive breast cancer this year in American women.
Significantly higher risk
A woman with a history of cancer in one breast is three to four times likelier to develop a new breast cancer, unrelated to the first one, in either the other breast or in another part of the same breast. This is different than a recurrence of the previous breast cancer.
Getting older. Your risk for breast cancer increases as you age. About 77% of women diagnosed with breast cancer each year are over age 50, and almost 50% are age 65 and older. Consider this: In women 40 to 49 years of age, there is a one in 68 risk of developing breast cancer. In the 50 to 59 age group, that risk increases to one in 37.
Direct family history. Having a mother, sister, or daughter (“first-degree” relative) who has breast cancer puts a woman at higher risk for the disease. The risk is even greater if this relative developed breast cancer before menopause and had cancer in both breasts. Having one first-degree relative with breast cancer approximately doubles a woman’s risk, and having two first-degree relatives increases her risk fivefold. Having a male blood relative with breast cancer will also increase a woman’s risk of the disease.
Genetics. Carriers of alterations in either of two familial breast cancer genes called BRCA1 or BRCA2 are at higher risk. Women with an inherited alteration in either of these genes have up to an 85% chance of developing breast cancer in their lifetime.
Breast lesions. A previous breast biopsy result of atypical hyperplasia (lobular or ductal) or lobular carcinoma in situ increases a woman’s breast cancer risk by four to five times.
Slightly higher risk
Distant family history. This refers to breast cancer in more distant relatives such as aunts, grandmothers, and cousins.
Previous abnormal breast biopsy. Women with earlier biopsies showing any of the following have a slight increased risk: fibroadenomas with complex features, hyperplasia without atypia, sclerosing adenosis, and solitary papilloma
Age at childbirth. Having your first child after age 35 or never having children puts you at higher risk.
Early menstruation. Your risk increases if you began menstruating before age 12.
Late menopause. If you begin menopause after age 55, your risk increases.
Weight. Being overweight (especially in the waist), with excess caloric and fat intake, increases your risk, especially after menopause.
Excessive radiation. This is especially true for women who were given radiation for postpartum mastitis, received prolonged fluoroscopic X-rays for tuberculosis, or who were exposed to a large amount of radiation before age 30 — usually as treatment for cancers such as lymphoma.
Other cancer in the family. A family history of cancer of the ovaries, cervix, uterus, or colon increases your risk.
Heritage. Female descendents of Eastern and Central European Jews (Ashkenazi) are at increased risk.
Alcohol. Use of alcohol is linked to increased risk of developing breast cancer. Compared with nondrinkers, women who consume one alcoholic drink a day have a very small increase in risk, and those who have 2 to 5 drinks daily have about 1.5 times the risk of women who do not drink.
Race. Caucasian women are at a slightly higher risk of developing breast cancer than are African-American, Asian, Hispanic, and Native American women. The exception to this is African-American women, who are more likely to have breast cancer than whites under the age of 40.
Hormone Replacement Therapy (HRT). Long-term use of combined estrogen and progesterone increases the risk of breast cancer. This risk seems to return to that of the general population after discontinuing them for five years or longer.
Regular Exercise Can Help Lower Breast Cancer Risk
Exercise can lower women’s risk of breast cancer, but how much exercise is enough and at what age do women have to be physically active to benefit?
Those are the questions that Lauren McCullough, a doctoral candidate in epidemiology at the University of North Carolina, Chapel Hill, and her colleagues sought to answer in a new study published in the journal Cancer. They found that women who exercised about two hours a day five days a week were about 30% less likely to develop breast cancer than less active women. The intensity of the exercise didn’t seem to matter; all it took was moderate physical activity, which could include gardening, walking or doing household chores, for the women to benefit.
McCullough’s study included 1,504 women with breast cancer and 1,555 similar women without the disease, aged 20 to 98 years old, enrolled in the Long Island Breast Cancer Study Project. As part of the project, the women answered questions about their physical activity over their lifetimes — any recreational exercise they did for at least an hour per week for three months or more. The researchers then calculated a lifetime composite score for physical activity that they used to compare across the participants.
Overall, women who did any exercise had a 6% lower risk of breast cancer than those who did not, but certain subgroups of women enjoyed even larger benefits. The effect was strongest among women who had children and exercised about 10 to 19 hours each week — either during their reproductive years or after menopause; for them, exercise was associated with a 30% lower risk of breast cancer during the study period, compared with women who exercised less, or not at all.