Breast cancer facts, causes, risk factors, treatments, lifestyle choices
How Many Women Get Breast Cancer?
Breast cancer is the most common cancer among women in the United States, other than skin cancer. It is the second leading cause of cancer death in women, after lung cancer.
About 182,460 women in the United States will be found to have invasive breast cancer in 2008. About 40,480 women will die from the disease this year. Right now there are about two and a half million breast cancer survivors in the United States.
The chance of a woman having invasive breast cancer some time during her life is about 1 in 8. The chance of dying from breast cancer is about 1 in 35. Breast cancer death rates are going down. This is probably the result of finding the cancer earlier and improved treatment.
What Causes Breast Cancer?
Certain changes in DNA can cause normal breast cells to become cancerous. DNA is the chemical in each of our cells that makes up our genes -- the instructions for how our cells work. Some inherited DNA changes can increase the risk for developing cancer and are responsible for the cancers that run in some families. But most breast cancer DNA changes happen in single breast cells during a woman's life rather than having been inherited. These are called acquired changes, and most breast cancers have several of these acquired gene mutations. But so far, the causes of most acquired mutations that could lead to breast cancer remain unknown.
While we do not yet know exactly what causes breast cancer, we do know that certain risk factors are linked to the disease. A risk factor is anything that affects a person's chance of getting a disease such as cancer. Different cancers have different risk factors. Some risk factors, such as smoking, drinking, and diet are linked to things a person does. Others, like a person's age, race, or family history, can't be changed. But risk factors don't tell us everything. Having a risk factor, or even several, doesn't mean that a person will get the disease. Some women who have one or more risk factors never get breast cancer. And most women who do get breast cancer don't have any risk factors. While all women are at risk for breast cancer, the factors listed below can increase a woman's chances of having the disease.
Although many risk factors may increase your chance of developing 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 just how this happens is not fully understood.
Risk factors you cannot change
Gender: Simply being a woman is the main risk for breast cancer. While men also get the disease, it is about 100 times more common in women than in men.
Age: The chance of getting breast cancer goes up as a woman gets older. About 2 out of 3 women with invasive breast cancer are age 55 or older when the cancer is found.
Genetic risk factors: About 5 percent to 10 percent of breast cancers are thought to be linked to inherited changes (mutations) in certain genes. The most common gene changes are those of the BRCA1 and BRCA2 genes. Women with these gene changes have up to an 80 percent chance of getting breast cancer during their lifetimes. Other gene changes may raise breast cancer risk as well.
Family history: Breast cancer risk is higher among women whose close blood relatives have this disease. The relatives can be from either the mother's or father's side of the family. Having a mother, sister, or daughter with breast cancer about doubles a woman's risk. (It's important to note that 70 percent to 80 percent of women who get breast cancer do not have a family history of this disease.)
Personal history of breast cancer: A woman with cancer in one breast has a greater chance of getting a new cancer in the other breast or in another part of the same breast. This is different from a return of the first cancer (which is called recurrence).
Race: White women are slightly more likely to get breast cancer than are African-American women. But African American women are more likely to die of this cancer. At least part of the reason seems to be because African-American women have faster growing tumors. Asian, Hispanic, and American Indian women have a lower risk of getting breast 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. Dense breast tissue can also make it harder for doctors to spot problems on mammograms.
Menstrual periods: Women who began having periods early (before age 12) or who went through the change of life (menopause) after the age of 55 have a slightly increased risk of breast cancer. They have had more menstrual periods and as a result have been exposed to more of the hormones estrogen and progesterone.
Earlier breast radiation: Women who have had radiation treatment to the chest area (as treatment for another cancer) earlier in life have a greatly increased risk of breast cancer.
Treatment with DES: In the past, some pregnant women were given the drug DES (diethylstilbestrol) because it was thought to lower their chances of losing the baby (miscarriage). Recent studies have shown that these women (and their daughters who were exposed to DES while in the womb), have a slightly increased risk of getting breast cancer. For more information on DES see our document, DES Exposure: Questions and Answers.
Breast cancer risk and lifestyle choices
Not having children or having them later in life: Women who have had not had children, or who had their first child after age 30, have a slightly higher risk of breast cancer. Being pregnant more than once and at an early age reduces breast cancer risk. Pregnancy reduces a woman's total number of lifetime menstrual cycles, which may be the reason for this effect.
Recent use of birth control pills: Studies have found that women who are using birth control pills have a slightly greater risk of breast cancer than women who have never used them. Women who stopped using the pill more than 10 years ago do not seem to have any increased risk. It's a good idea to talk to your doctor about the risks and benefits of birth control pills.
Postmenopausal hormone therapy (PHT): Postmenopausal hormone therapy (also known as hormone replacement therapy or HRT), has been used for many years to help relieve symptoms of menopause and to help prevent thinning of the bones (osteoporosis). There are 2 main types of PHT. For women who still have a womb (uterus), doctors generally prescribe estrogen and progesterone (known as combined PHT). Estrogen alone can increase the risk of cancer of the uterus, so progesterone is added to help prevent this. For women who no longer have a uterus (those who've had a hysterectomy), estrogen alone can be prescribed. This is commonly known as estrogen replacement therapy (ERT).
Combined PHT: It has become clear that long-term use (several years or more) of combined PHT increases the risk of breast cancer and may increase the chances of dying of breast cancer. The breast cancer may also be found at a more advanced stage, perhaps because PHT seems to reduce the effectiveness of mammograms. Five years after stopping PHT, the breast cancer risk seems to drop back to normal.
ERT: The use of estrogen alone does not seem to increase the risk of developing breast cancer much, if at all. But when used long-term (for more than 10 years), some studies have found that ERT increases the risk of ovarian and breast cancer.
At this time, there are few strong reasons to use PHT, other than for short-term relief of menopausal symptoms. Because there are other factors to think about, you should talk with your doctor about the pros and cons of using PHT. If a woman and her doctor decide to try PHT for symptoms of menopause, it is usually best to use it at the lowest dose that works for her and for as short a time as possible.
Not breast-feeding: Some studies have shown that breast-feeding slightly lowers breast cancer risk, especially if the breast-feeding lasts 11⁄2 to 2 years. This could be because breast-feeding lowers a woman's total number of menstrual periods, as does pregnancy
Alcohol: Use of alcohol is clearly linked to an increased risk of getting breast cancer. Women who have one drink a day have a very small increased risk. Those who have 2 to 5 drinks daily have about 11⁄2 times the risk of women who drink no alcohol. The American Cancer Society suggests limiting the amount you drink to one drink a day.
Being overweight or obese: Being overweight or obese is linked to a higher risk of breast cancer, especially for women after change of life and if the weight gain took place during adulthood. Also, the risk seems to be higher if the extra fat is in the waist area. But the link between weight and breast cancer risk is complex, and studies of fat in the diet as it relates to breast cancer risk have often given conflicting results. The American Cancer Society recommends you maintain a healthy weight throughout your life and avoid gaining too much weight.
Lack of exercise: Studies show that exercise reduces breast cancer risk. The only question is how much exercise is needed. One study found that as little as 1 hour and 15 minutes to 21⁄2 hours of brisk walking per week reduced the risk by 18 percent. Walking 10 hours a week reduced the risk a little more. The American Cancer Society suggests that you exercise for 45 to 60 minutes 5 or more days a week.
Uncertain risk factors
High fat diets: Studies of fat in the diet have not clearly shown that this is a breast cancer risk factor. Most studies found that breast cancer is less common in countries where the typical diet is low in fat. On the other hand, many studies of women in the United States have not found breast cancer risk to be linked to how much fat they ate. Researchers are still not sure how to explain this difference. More research is needed to better understand the effect of the types of fat eaten and body weight on breast cancer risk.
The American Cancer Society recommends eating a healthy diet that includes 5 or more servings of vegetables and fruits each day, choosing whole grains over processed (refined) grains, and limiting the amount of processed and red meats.
Antiperspirants and bras: Internet e-mail rumors have suggested that underarm antiperspirants can cause breast cancer. There is very little evidence to support this idea. Also, there is no evidence to support the idea that under wire bras cause breast cancer.
Abortions: Several studies show that induced abortions do not increase the risk of breast cancer. Also, there is no evidence to show a direct link between miscarriages and breast cancer. For more detailed information, see our document, Can Having an Abortion Cause or Contribute to Breast Cancer?
Breast implants: Silicone breast implants can cause scar tissue to form in the breast. But several studies have found that this does not increase breast cancer risk. If you have breast implants, you might need special x-ray pictures during mammograms.
Pollution: A lot of research is being done to learn how the environment might affect breast cancer risk. At this time, research
does not show a clear link between breast cancer risk and environmental pollutants such as pesticides and PCBs.
Tobacco Smoke: Most studies have found no link between active cigarette smoking and breast cancer. An issue that continues to be a focus of research is whether secondhand smoke (smoke from another person's cigarette) may increase the risk of breast cancer. But the evidence about secondhand smoke and breast cancer risk in human studies is not clear. In any case, a possible link to breast cancer is yet another reason to avoid being around secondhand smoke.
Night Work: A few studies have suggested that women who work at night (nurses on the night shift, for example) have a higher risk of breast cancer. This is a fairly recent finding, and more studies are being done to look at this issue.
How Is Breast Cancer Found?
The term screening refers to tests and exams used to find a disease like cancer in people who do not have any symptoms. The earlier breast cancer is found, the better the chances that treatment will work. The goal is to find cancers before they start to cause symptoms. The size of a breast cancer and how far it has spread are the most important factors in predicting the outlook for the patient. Most doctors feel that early detection tests for breast cancer save many thousands of lives each year. Following the guidelines given here improves the chances that breast cancer can be found at an early stage and treated with success.
ACS recommendations for early breast cancer detection
The ACS recommends the following guidelines for finding breast cancer early in women without symptoms:
Mammogram: Women age 40 and older should have a screening mammogram every year and should continue to do so for as long as they are in good health. While mammograms can miss some cancers, they are still a very good way to find breast cancer.
Clinical breast exam: Women in their 20s and 30s should have a clinical breast exam (CBE) as part of a regular exam by a health expert, at least every 3 years. After age 40, women should have a breast exam by a health expert every year. It might be a good idea to have the CBE shortly before the mammogram. You can use the exam to learn what your own breasts feel like.
Breast self-exam (BSE): BSE is an option for women starting in their 20s. Women should be told about the benefits and limitations of BSE. Women should report any changes in how their breasts look or feel to their health professional right away.
Research has shown that BSE plays a small role in finding breast cancer compared with finding a breast lump by chance or simply being aware of what is normal for each woman. If you decide to do BSE, you should have your doctor or nurse check your method to make sure you are doing it right. If you do BSE on a regular basis, you get to know how your breasts normally look and feel. Then you can more easily notice changes. But it's OK not to do BSE or not to do it on a fixed schedule.
The goal, with or without BSE, is to see your doctor right away if you notice any of these changes: a lump or swelling, skin irritation or dimpling, nipple pain or the nipple turning inward, redness or scaliness of the nipple or breast skin, or a discharge other than breast milk. But remember that most of the time these breast changes are not cancer.
Women at high risk: Women with a higher risk of breast cancer should talk with their doctor about the best approach for them. This might mean starting mammograms when they are younger, having extra screening tests, or having more frequent exams.
A mammogram is an x-ray of the breast. This test is used to look for breast disease in women who do not seem to have breast problems. It can also be used when women have symptoms such as a lump, skin change, or nipple discharge.
During a mammogram, the breast is pressed between 2 plates to flatten and spread the tissue. The pressure lasts only for a few seconds. Although this may cause some pain for a moment, it is needed to get a good picture. Very low levels of radiation are used. While many people are worried about exposure to x-rays, the low level of radiation used for mammograms does not increase the risk of breast cancer. To put dose into perspective, if a woman with breast cancer is treated with radiation, she will get around 5,000 rads (a term used to measure radiation dose). If she had a mammograms every year from age 40 to age 90, she will have had 20 to 40 rads total.
For the mammogram, you undress above the waist. You will have a wrap to cover yourself. A technologist (most often a woman) will position your breast correctly for the test. The pressure lasts only a few seconds while the picture is taken. The whole procedure takes about 20 minutes. You should get your results within 30 days or even sooner.
About 1 in 10 women who get a mammogram will need more pictures taken. But most of these women do not have breast cancer, so don't be alarmed if this happens to you. Only 2 to 4 of every 1,000 mammograms leads to a diagnosis of cancer.
Women with a higher risk of breast cancer should talk with their doctor about the best approach for them. They may benefit from starting mammograms when they are younger, having them more often, or having other tests along with them. If you are at higher risk, your doctor might recommend an ultrasound or MRI (magnetic resonance imaging) be done along with your mammograms.
Medicare, Medicaid, and most private health plans cover all or part of the cost of this test. Call us at 1-800-ACS-2345 (1-800-227-2345) for information about facilities in your area. Breast cancer testing is available to women without health insurance for free or at very little cost through a special program called the National Breast and Cervical Cancer Early Detection Program (NBCCEDP). Your state's Department of Health will have information about this program. There is also a new program to help pay for breast cancer treatment for women in need. To learn more about these programs, you can contact the Centers for Disease Control and Prevention at 1-800-CDC INFO (1-800-232-4636) or on the Internet at www.cdc.gov/cancer/nbccedp.
Clinical breast exam
A clinical breast exam (CBE) is an exam of your breasts by a health expert such as a doctor, nurse practitioner, nurse, or physician assistant. For this exam, you undress from the waist up. The examiner will first look at your breasts for changes in size or shape. Then, using the pads of the fingers, she or he will gently feel your breasts for lumps. The area under both arms will also be checked. This is a good time to learn how to do breast self-exam if you don't already know how.
Breast awareness and breast self-exam
Women should be aware of how their breasts normally look and feel and report any changes to their doctor right away. Finding a change does not mean that you have cancer.
By being aware of how your own breasts look and feel, you are likely to notice any changes that might take place. You can also choose to use a step-by-step approach to checking your breasts on a set schedule. The best time to do breast self-examination (BSE) is when your breasts are not tender or swollen. If you find any changes, see your doctor right away.
Women with breast implants can do BSE. It may help to have the surgeon help identify the edges of the implant so that you know what you are feeling. It may be that the implants push out the breast tissue and actually make it easier to examine.
It's OK for women not to do BSE or to do it once in a while. We have detailed information on how to do BSE for women who want to do it. You can find it on our Web site or you can call and ask for it.
MRI (magnetic resonance imaging)
For certain women at high risk for breast cancer, screening MRI is recommended along with a yearly mammogram. It is not generally recommended as a screening tool by itself as it may miss some cancers that mammograms would find. MRI also costs more than mammograms. Most major insurance companies will likely pay for a screening MRI if a woman can be shown to be at high risk, but it's not yet clear if all companies will do so. More details about MRI can be found below.
Symptoms of breast cancer
The widespread use of screening mammograms has increased the number of breast cancers found before they cause any symptoms, but some are still missed.
The most common sign of breast cancer is a new lump or mass. A lump that is painless, hard, and has uneven edges is more likely to be cancer. But some cancers are tender, soft, and rounded. So it's important to have anything unusual checked by a doctor.
Other signs of breast cancer include the following:
swelling of all or part of the breast
skin irritation or dimpling
nipple pain or the nipple turning inward
redness, scaliness, or thickening of the nipple or breast skin
a nipple discharge other than breast milk
a lump in the underarm area