Importance of Finding Breast Cancer Early

The goal of screening exams for early breast cancer detection is to find cancers before they start to cause symptoms. Screening refers to tests and exams used to find a disease, such as cancer, in people who do not have any symptoms. Early detection means using an approach that allows earlier diagnosis of breast cancer than otherwise might have occurred.

Breast cancers that are found because they are causing symptoms tend to be larger and are more likely to have already spread beyond the breast. In contrast, breast cancers found during screening exams are more likely to be smaller and still confined to the breast. The size of a breast cancer and how far it has spread are some of the most important factors in predicting the prognosis (outlook) of a woman with this disease.

Most doctors feel that early detection tests for breast cancer save many thousands of lives each year, and that many more lives could be saved if even more women and their health care providers took advantage of these tests. Following the American Cancer Society's guidelines for the early detection of breast cancer improves the chances that breast cancer can be diagnosed at an early stage and treated successfully.

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 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 breast cancer has a risk factor, there is no way to prove that it actually caused 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 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 changes.

Risk Factors You Cannot Change

Gender

Simply being a woman is the main risk factor for developing breast cancer. Although women have many more breast cells than men, the main reason they develop more breast cancer is because their breast cells are constantly exposed to the growth-promoting effects of the female hormones estrogen and progesterone. Men can develop breast cancer, but this disease is about 100 times more common among women than men.

Aging

Your risk of developing breast cancer increases as you get older. About 1 out of 8 invasive breast cancer diagnoses are among women younger than 45, while about 2 out of 3 women with invasive breast cancer are age 55 or older when they are diagnosed.

Genetic Risk Factors

About 5% to 10% of breast cancer cases are thought to be hereditary, resulting directly from gene changes (called mutations) inherited from a parent.

BRCA1 and BRCA2: The most common inherited mutations are those of the BRCA1 and BRCA2 genes. Normally, these genes help to prevent cancer by making proteins that keep cells from growing abnormally. However, if you have inherited a mutated copy of either gene from a parent, you are at increased risk for breast cancer.

Women with an inherited BRCA1 or BRCA2 mutation have up to an 80% chance of developing breast cancer during their lifetime, and when they do it is often at a younger age than in women who are not born with one of these gene mutations. Women with these inherited mutations also have an increased risk for developing ovarian cancer. Although BRCA mutations are found most often in Jewish women of Ashkenazi (Eastern Europe) origin, they are also seen in African-American women and Hispanic women and can occur in any racial or ethnic group.

Other genes have been discovered that might also lead to inherited breast cancers. These genes do not impart the same level of breast cancer risk as the BRCA genes, and are not frequent causes of familial (inherited) breast cancer.

ATM: The ATM gene normally helps repair damaged DNA. Certain families with a high rate of breast cancer have been found to have mutations of this gene.

CHEK2: The CHEK2 gene increases breast cancer risk about twofold when it is mutated. In women who carry the CHEK2 mutation and have a strong family history of breast cancer, the risk is greatly increased.

p53: Inherited mutations of the p53 tumor suppressor gene can also increase the risk of developing breast cancer, and several other cancers such as leukemia, brain tumors, and/or sarcomas (cancer of bones or connective tissue). The Li-Fraumeni syndrome, named after the 2 researchers who described this inherited cancer syndrome, is a rare cause of breast cancer.

PTEN: The PTEN gene normally helps regulate cell growth. Inherited mutations in this gene cause Cowden syndrome, a rare disorder in which people are at increased risk for both benign and malignant breast tumors, as well as growths in the digestive tract, thyroid, uterus, and ovaries.

Genetic testing: If you are considering genetic testing, it is strongly recommended that first you talk to a genetic counselor, nurse, or doctor qualified to explain and interpret the results of these tests. It is very important to understand and carefully weigh the benefits and risks of genetic testing before these tests are done. Testing is expensive and is not covered by some health insurance plans. There have been concerns that people with abnormal genetic test results might not be able to get life insurance or that coverage may only be available at a much higher cost, but many states have passed laws that prevent insurance companies from denying insurance on the basis of genetic testing.

For more information, see the separate American Cancer Society document, Genetic Testing: What You Need to Know. You may also want to visit the National Cancer Institute Web site (www.cancer.gov/cancertopics/Genetic-Testing-for-Breast-and-Ovarian-Cancer-Risk) for information about genetic testing and breast cancer. To learn about state laws against genetic testing discrimination, you may want to visit the Web site of the National Conference of State Legislatures (www.ncsl.org/programs/health/genetics/ndishlth.htm).

Family History of Breast Cancer

Breast cancer risk is higher among women whose close blood relatives have this disease.

Having 1 first-degree relative (mother, sister, or daughter) with breast cancer almost doubles a woman's risk. Having 2 first-degree relatives increases her risk about 5-fold. Although the exact risk is not known, women with a family history of breast cancer in a father or brother also have an increased risk of breast cancer. Overall, about 20% to 30% of women with breast cancer have a family member with this disease. (It's important to note this means that 70% to 80% 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 3- to 4-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

White women are slightly more likely to develop breast cancer than are African-American women. However, African-American women are more likely to die of this cancer. At least part of this seems to be because African-American women tend to have more aggressive tumors, although the reasons for this are not known. Asian, Hispanic, and Native American women have a lower risk of developing and dying from breast cancer.

Abnormal Breast Biopsy Results

Some types of benign breast conditions are more closely linked to breast cancer risk than others. Doctors often divide benign breast conditions into 3 general groups, depending on how they affect this risk: non-proliferative lesions, proliferative lesions without atypia, and proliferative lesions with atypia.

The non-proliferative lesions (those without any overgrowth of breast tissue) do not seem to affect breast cancer risk, or if they do it is to a very small extent. They include:

• fibrosis
• cysts
• mild hyperplasia
• adenosis (non-sclerosing)
• simple fibroadenoma
• phyllodes tumor (benign)
• a single papilloma
• fat necrosis
• mastitis
• duct ectasia
• other benign tumors (lipoma, hamartoma, hemangioma, neurofibroma)

The proliferative lesions without atypia (those with excessive growth of cells in the ducts or lobules of the breast tissue) seem to raise a woman�s risk of breast cancer slightly (1 � to 2 times normal). They include:

• usual ductal hyperplasia (without atypia)
• complex fibroadenoma
• sclerosing adenosis
• several papillomas or papillomatosis
• radial scar

The proliferative lesions with atypia (those with excessive growth of cells in the ducts or lobules of the breast tissue, and in which the cells no longer appear normal) have a stronger effect on breast cancer risk, raising it 4 to 5 times higher than normal. They include:

• atypical ductal hyperplasia (ADH)
• atypical lobular hyperplasia (ALH)

Women with a family history of breast cancer and either hyperplasia or atypical hyperplasia have an even higher risk of developing a breast cancer.

Menstrual Periods

Women who started menstruating at an early age (before age 12) or who went through menopause at a late age (after age 55) have a slightly higher risk of breast cancer. This may be related to a higher 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) are at significantly increased risk for breast cancer. This varies with the age of the patient at the time of radiation. If chemotherapy was also given, the risk may be lowered if the chemotherapy stopped ovarian hormone production. The risk of developing breast cancer appears to be highest if the breast was still in development (during adolescence) when the radiation was given.

Diethylstilbestrol (DES) Exposure

From the 1940s through the 1960s some pregnant women were given an estrogen-like drug called DES because it was thought to lower their chances of losing the baby (miscarriage). Studies have shown that these women have a slightly increased risk of developing breast cancer. Recent findings have also suggested that women whose mothers took DES during pregnancy may have a higher risk for breast cancer. For more information on DES see the separate American Cancer Society document, DES Exposure: Questions and Answers.

Lifestyle-Related Factors and Breast Cancer Risk

Not Having Children, or Having Them Later in Life

Women who have not had children, or who had their first child after age 30 have a slightly higher breast cancer risk. Having multiple pregnancies and becoming pregnant at an early age reduces breast cancer risk.

Oral Contraceptive Use

It is still not certain what part oral contraceptives (birth control pills) might play in breast cancer risk. Studies have suggested that women now using oral contraceptives have a slightly greater risk of breast cancer than women who have never used them, but this risk seems to decline once their use is stopped. Women who stopped using oral contraceptives more than 10 years ago do not appear to have any increased breast cancer risk. When thinking about using oral contraceptives, women should discuss their other risk factors for breast cancer with their health care team.

Postmenopausal Hormone Therapy or Hormone Replacement Therapy

Postmenopausal hormone therapy, also known as hormone replacement therapy (HRT), has been used for many years to help relieve symptoms of menopause and to help prevent osteoporosis (thinning of the bones). Earlier studies suggested it might have other health benefits as well, but these have not been found in more recent, better designed studies.

There are 2 main types of PHT. For women who still have a uterus (womb), doctors generally prescribe estrogen and progesterone (known as combined PHT). Because estrogen alone can increase the risk of developing cancer of the uterus, 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 postmenopausal hormone therapy increases the risk of breast cancer, and may also increase the chances of dying of breast cancer. Several large studies, including the Women's Health Initiative (WHI), have found that there is an increased risk of breast cancer related to the use of combined PHT. Combined PHT also increases the likelihood that the cancer may be found at a more advanced stage, possibly because it reduces the effectiveness of mammograms.

The increased risk from combined PHT appears to apply only to current and recent users. A woman's breast cancer risk seems to return to that of the general population within 5 years of stopping combined PHT.

ERT: The use of estrogen alone does not appear to increase the risk of developing breast cancer significantly, if at all. But when used long term (for more than 10 years), ERT has been found to increase the risk of ovarian and breast cancer in some studies.

At this time there appear to be few strong reasons to use postmenopausal hormone therapy (combined PHT or ERT), other than possibly for the short-term relief of menopausal symptoms. Along with the increased risk of breast cancer, combined PHT also appears to increase the risk of heart disease, blood clots, and strokes. It does lower the risk of colorectal cancer and osteoporosis, but this must be weighed against the possible harms, and it should be noted that there are other effective ways to prevent osteoporosis. While ERT does not seem to have much effect on the risk of breast cancer, it does increase the risk of stroke.

The decision to use PHT should be made by a woman and her doctor after weighing the possible risks and benefits (including the severity of her menopausal symptoms), and considering her other risk factors for heart disease, breast cancer, and osteoporosis.

Breast-feeding

Some studies suggest that breast-feeding may slightly lower breast cancer risk, especially if it is continued for 1� to 2 years. But this has been a difficult area to study, especially in countries such as the United States, where long-term breast-feeding is uncommon.

The explanation for this possible effect may be that breast-feeding reduces a woman's total number of lifetime menstrual cycles. This may be similar to the reduction of risk due to starting menstrual periods at a later age or due to early menopause, which also decrease the total number of menstrual cycles.

Alcohol

Use of alcohol is clearly linked to an increased risk of developing breast cancer. The risk increases with the amount of alcohol consumed. Compared with non-drinkers, women who consume 1 alcoholic drink a day have a very small increase in risk. Those who have 2 to 5 drinks daily have about 1� times the risk of women who drink no alcohol. Alcohol is also known to increase the risk of developing cancers of the mouth, throat, esophagus, and liver. The American Cancer Society recommends limiting your consumption of alcohol.

Being Overweight or Obese

Being overweight or obese has been found to increase breast cancer risk, especially for women after menopause. Before menopause your ovaries produce most of your estrogen, and fat tissue produces a small amount of estrogen. After menopause, once the ovaries stop making estrogen, most of a woman's estrogen comes from fat tissue. Having more fat tissue after menopause can increase your estrogen levels and thereby increase your likelihood of developing breast cancer.

The connection between weight and breast cancer risk is complex, however. For example, risk appears to be increased for women who gained weight as an adult but may not be increased among those who have been overweight since childhood. Also, excess fat in the waist area may affect risk more than the same amount of fat in the hips and thighs. Researchers believe that fat cells in various parts of the body have subtle differences in their metabolism that may explain this observation.

The American Cancer Society recommends you maintain a healthy weight throughout your life by balancing your food intake with physical activity and avoiding excessive weight gain.

Physical Activity

Evidence is growing that physical activity in the form of exercise reduces breast cancer risk. The only question is how much exercise is needed. In one study from the Women's Health Initiative, as little as 1� to 2� hours per week of brisk walking reduced a woman's risk by 18%. Walking 10 hours a week reduced the risk a little more.

To reduce your risk of breast cancer, the American Cancer Society recommends that you engage in 45 to 60 minutes of intentional physical activity 5 or more days a week.

Factors with Uncertain, Controversial, or Unproven Effect on Breast Cancer Risk

High-fat Diets

Studies of fat in the diet have not clearly shown that this is a breast cancer risk factor.

Most studies have found that breast cancer is less common in countries where the typical diet is low in total fat, low in polyunsaturated fat, and low in saturated fat. On the other hand, many studies of women in the United States have not found breast cancer risk to be related to dietary fat intake. Researchers are still not sure how to explain this apparent disagreement. Many scientists note that studies comparing diet and breast cancer risk in different countries are complicated by other differences (such as activity level, intake of other nutrients, and genetic factors) that might also alter breast cancer risk.

More research is needed to better understand the effect of the types of fat eaten and body weight on breast cancer risk. But it is clear that calories do count, and fat is a major source of these. A diet high in fat has also been shown to influence the risk of developing several other types of cancer, and intake of certain types of fat is clearly related to heart disease risk.

The American Cancer Society recommends eating a healthy diet with an emphasis on plant sources. This includes eating 5 or more servings of vegetables and fruits each day, choosing whole grains over processed (refined) grains, and limiting consumption of processed and red meats. Antiperspirants

Internet email rumors have suggested that chemicals in underarm antiperspirants are absorbed through the skin, interfere with lymph circulation, and cause toxins to build up in the breast, eventually leading to breast cancer. There is very little laboratory or population-based evidence to support this rumor.

One small study recently found trace levels of parabens (used as preservatives in antiperspirants and other products), which have weak estrogen-like properties, in a small sample of breast cancer tumors. However, the study did not look at whether parabens caused the tumors. This was a preliminary finding, and more research is needed to determine what effect, if any, parabens may have on breast cancer risk. On the other hand, a large population-based study found no increase in breast cancer in women who used underarm antiperspirants or shaved their underarms.

Bras

Internet e-mail rumors and at least one book have suggested that bras cause breast cancer by obstructing lymph flow. There is no good scientific or clinical basis for this claim. Women who do not wear bras regularly are more likely to be thinner, which would likely contribute to any perceived difference in risk.

Induced Abortion

Several studies have provided very strong data that neither induced abortions nor spontaneous abortions (miscarriages) have an overall effect on the risk of breast cancer. For more detailed information, see the separate American Cancer Society document, Can Having an Abortion Cause or Contribute to Breast Cancer?

Breast Implants

Several studies have found that breast implants do not increase breast cancer risk, although silicone breast implants can cause scar tissue to form in the breast. Implants make it harder to see breast tissue on standard mammograms, but additional x-ray pictures called implant displacement views can be used to more completely examine the breast tissue.

Environmental Pollution

A great deal of research has been reported and more is being done to understand environmental influences on breast cancer risk. The goal is to determine their possible relationships to breast cancer. Of special interest are compounds in the environment that have estrogen-like properties, which could in theory affect breast cancer risk. While this issue understandably invokes a great deal of public concern, at this time research does not show a clear link between breast cancer risk and exposure to environmental pollutants, such as the pesticide DDE (chemically related to DDT) and PCBs (polychlorinated biphenyls).

Tobacco Smoke

Most studies have found no link between cigarette smoking and breast cancer. Though active smoking has been suggested to increase the risk of breast cancer in some studies, the issue remains controversial.

An issue that continues to be a focus of scientific research is whether secondhand smoke may increase the risk of breast cancer. Both mainstream and secondhand smoke contain chemicals that, in high concentrations, cause breast cancer in rodents. Chemicals in tobacco smoke reach breast tissue and are found in breast milk.

The evidence regarding secondhand smoke and breast cancer risk in human studies is controversial, at least in part because the risk has not been shown to be increased in smokers. One possible explanation for this is that tobacco smoke may have different effects on breast cancer risk in smokers compared to those who are just exposed to secondhand smoke.

A report from the California Environmental Protection Agency in 2005 concluded that the evidence regarding secondhand smoke and breast cancer is "consistent with a causal association" in younger, mainly premenopausal women. The 2006 US Surgeon General's report, The Health Consequences of Involuntary Exposure to Tobacco Smoke, concluded that there is "suggestive but not sufficient" evidence of a link at this point. In any case, this possible link to breast cancer is yet another reason to avoid secondhand smoke.

Night Work

Several studies have suggested that women who work at night, such as nurses on night shift, may have an increased risk of developing breast cancer. This is a fairly recent finding, and more studies are in progress to look at this issue. According to some researchers, the effect may be due to disruption in melatonin, a hormone that is affected by light, but other hormones are also being studied.

American Cancer Society Recommendations for Early Breast Cancer Detection in Women Without Breast Symptoms

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.

• Current evidence supporting mammograms is even stronger than in the past. In particular, recent evidence has confirmed that mammograms offer substantial benefit for women in their 40s. Women can feel confident about the benefits associated with regular mammograms for finding cancer early. However, mammograms also have limitations. A mammogram will miss some cancers, and it sometimes leads to follow up of findings that are not cancer, including biopsies.
• Women should be told about the benefits, limitations, and potential harms linked with regular screening. Mammograms can miss some cancers. But despite their limitations, they remain a very effective and valuable tool for decreasing suffering and death from breast cancer.
• Mammograms for older women should be based on the individual, her health, and other serious illnesses, such as congestive heart failure, end-stage renal disease, chronic obstructive pulmonary disease, and moderate-to-severe dementia. Age alone should not be the reason to stop having regular mammograms. As long as a woman is in good health and would be a candidate for treatment, she should continue to be screened with a mammogram.

Women in their 20s and 30s should have a clinical breast exam (CBE) as part of a periodic (regular) health exam by a health professional preferably every 3 years. After age 40, women should have a breast exam by a health professional every year.

• CBE is a complement to mammograms and an opportunity for women and their doctor or nurse to discuss changes in their breasts, early detection testing, and factors in the woman�s history that might make her more likely to have breast cancer.
• There may be some benefit in having the CBE shortly before the mammogram. The exam should include instruction for the purpose of getting more familiar with your own breast. Women should also be given information about the benefits and limitations of CBE and breast self exam (BSE). Breast cancer risk is very low for women in their 20s and gradually increases with age. Women should be told to promptly report any new breast symptoms to a health professional.

Breast self-examination (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 breast changes 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. Some women feel very comfortable doing BSE regularly (usually monthly) which involves a systematic step-by-step approach to examining the look and feel of one�s breasts. Other women are more comfortable simply looking and feeling their breasts in a less systematic approach, such as while showering or getting dressed or doing an occasional thorough exam. Sometimes, women are so concerned about "doing it right" that they become stressed over the technique. Doing BSE regularly is one way for women to know how their breasts normally look and feel and to notice any changes. The goal, with or without BSE, is to report any breast changes to a doctor or nurse right away.
• Women who choose to do BSE should have their BSE technique reviewed during their physical exam by a health professional. It is okay for women to choose not to do BSE or not to do it on a regular schedule. However, by doing the exam regularly, you get to know how your breasts normally look and feel and you can more readily detect any signs or symptoms If a change occurs, such as development of a lump or swelling, skin irritation or dimpling, nipple pain or retraction (turning inward), redness or scaliness of the nipple or breast skin, or a discharge other than breast milk. Should you notice any changes you should see your health care provider as soon as possible for evaluation. Remember that most of the time, however, these breast changes are not cancer.

Women at high risk (greater than 20% lifetime risk) should get an MRI and a mammogram every year. Women at moderately increased risk (15% to 20% lifetime risk) should talk with their doctors about the benefits and limitations of adding MRI screening to their yearly mammogram. Yearly MRI screening is not recommended for women whose lifetime risk of breast cancer is less than 15%.

• Women at high risk include those who:
  • have a known BRCA1 or BRCA2 gene mutation
  • have a first-degree relative (parent, brother, sister, or child) with a BRCA1 or BRCA2 gene mutation, and have not had genetic testing themselves
  • have a lifetime risk of breast cancer of 20% to 25% or greater, according to risk assessment tools that are based mainly on family history (see below)
  • had radiation therapy to the chest when they were between the ages of 10 and 30 years
  • have Li-Fraumeni syndrome, Cowden syndrome, or Bannayan-Riley-Ruvalcaba syndrome, or have one of these syndromes in first-degree relatives
• Women at moderately increased risk include those who:
  • have a lifetime risk of breast cancer of 15% to 20%, according to risk assessment tools that are based mainly on family history
  • have a personal history of breast cancer, ductal carcinoma in situ (DCIS), lobular carcinoma in situ (LCIS), atypical ductal hyperplasia (ADH), or atypical lobular hyperplasia (ALH)
  • have extremely dense breasts or unevenly dense breasts when viewed by mammograms
• If MRI is used, it should be in addition to, not instead of, a screening mammogram. This is because while an MRI is a more sensitive test (it's more likely to detect cancer than a mammogram), it may still miss some cancers that a mammogram would detect.
• For most women at high risk, screening with MRI and mammograms should begin at age 30 years and continue for as long as a woman is in good health. But because the evidence is limited regarding the best age at which to start screening, this decision should be based on shared decision making between patients and their health care providers, taking into account personal circumstances and preferences.
• Several risk assessment tools, with names such as BRCAPRO, the Claus model, and the Tyrer-Cuzick model, are available to help health professionals estimate a woman's breast cancer risk. These tools give approximate, rather than precise, estimates of breast cancer risk based on different combinations of risk factors and different data sets. As a result, they may give different risk estimates for the same woman. Their results should be discussed by a woman and her doctor when being used to decide on whether to start MRI screening.
• It is recommended that women who get screening MRI do so at a facility that can do an MRI-guided breast biopsy at the same time if needed. Otherwise, the woman will have to have a second MRI exam at another facility at the time of biopsy.
• There is no evidence at this time that MRI will be an effective screening tool for women at average risk. While MRI is more sensitive than mammograms, it also has a higher false-positive rate (where the test finds something that turns out not to be cancer), which would result in unneeded biopsies and other tests in a large portion of these women.

The American Cancer Society believes the use of mammograms, MRI (in women at high risk), clinical breast exams, and finding and reporting breast changes early, according to the recommendations outlined above, offers women the best chance to reduce their risk of dying from breast cancer. This approach is clearly better than any one exam or test alone. Without question, breast physical exam without a mammogram would miss the opportunity to detect many breast cancers that are too small for a woman or her doctor to feel but can be seen on mammograms. While mammograms are a sensitive screening method, a small percentage of breast cancers do not show up on mammograms but can be felt by a woman or her doctors. For women at high risk of breast cancer, such as those with BRCA gene mutations or a strong family history, both MRI and mammogram exams of the breast are recommended.

Mammograms

A mammogram is an x-ray of the breast. A diagnostic mammogram is used to diagnose breast disease in women who have breast symptoms. Screening mammograms are used to look for breast disease in women who are asymptomatic; that is, those who appear to have no breast problems. Screening mammograms usually involve 2 views (x-ray pictures taken from different angles) of each breast. Women who are breast-feeding can still get mammograms, although these are probably not quite as accurate.

For some women, such as those with breast implants (for augmentation or as reconstruction after mastectomy), additional pictures may be needed to include as much breast tissue as possible. Breast implants make it harder to see breast tissue on standard mammograms, but additional x-ray pictures with implant displacement and compression views can be used to more completely examine the breast tissue. If you have implants it is important that you have your mammograms done by someone skilled in the techniques used for women with implants.

Although breast x-rays have been performed for more than 70 years, modern mammography has only existed since 1969. That was the first year x-ray units dedicated to breast imaging were available. Modern mammogram equipment designed for breast x-rays uses very low levels of radiation, usually about a 0.1 to 0.2 rad dose per x-ray (a rad is a measure of radiation dose).

Strict guidelines are in place to ensure that mammogram equipment is safe and uses the lowest dose of radiation possible. Many people are concerned about the exposure to x-rays, but the level of radiation used in modern mammograms does not significantly increase the risk for breast cancer.

To put dose into perspective, a woman who receives radiation as a treatment for breast cancer will receive several thousand rads. If she had yearly mammograms beginning at age 40 and continuing until she was 90, she will have received 20 to 40 rads. As another example, flying from New York to California on a commercial jet exposes a woman to roughly the same amount of radiation as one mammogram.

For a mammogram, the breast is compressed between 2 plates to flatten and spread the tissue. Although this may be uncomfortable for a moment, it is necessary to produce a good, "readable" mammogram. The compression only lasts a few seconds. The entire procedure for a screening mammogram takes about 20 minutes.

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