Breast Cancer Screening Recommendations from the American Cancer Society
Screening refers to tests and exams used to find a disease, such as cancer, in people who do not have any symptoms. The goal of screening exams, such as mammograms, is to find cancers before they start to cause symptoms. Breast cancers that are found because they can be felt 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 small and still confined to the breast. The size of a breast cancer and how far it has spread are important factors in predicting the prognosis (survival outlook) for 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.
American Cancer Society recommendations for early breast cancer detection
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.
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:
Women at moderately increased risk include those who:
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 the Gail model, 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 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 right now 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 (it is more likely to find something that turns out not to be cancer). This would lead to unneeded biopsies and other tests in many 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 combined 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. Although 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.
A mammogram is an x-ray of the breast. A diagnostic mammogram is used to diagnose breast disease in women who have breast symptoms or an abnormal result on a screening mammogram. Screening mammograms are used to look for breast disease in women who are asymptomatic; that is, they appear to have no breast problems. Screening mammograms usually take 2 views (x-ray pictures taken from different angles) of each breast. For some patients, such as women with breast implants, more pictures may be needed to include as much breast tissue as possible. Women who are breast-feeding can still get mammograms, although these are probably not quite as accurate because the breast tissue tends to be dense.
Although breast x-rays have been done for more than 70 years, the modern mammogram has only existed since 1969. That was the first year x-ray units specifically for breast imaging were available. Modern mammogram equipment designed for breast x-rays uses very low levels of radiation, usually a dose of about 0.1 to 0.2 rads per picture (a rad is a measure of radiation dose).
Strict guidelines 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, if a woman with breast cancer is treated with radiation, she will receive around 5,000 rads. If she had yearly mammograms beginning at age 40 and continuing until she was 90, she will have received 20 to 40 rads.
For a mammogram, the breast is pressed 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. This procedure produces a black and white image of the breast tissue either on a large sheet of film or as a digital computer image that is read, or interpreted, by a radiologist (a doctor trained to interpret images from x-rays, ultrasound, MRI, and related tests).
Some advances in technology, such as digital mammography, may help doctors read mammograms more accurately. They are described here.
What the doctor looks for on your mammogram
The doctor reading the films will look for several types of changes:
Calcifications are tiny mineral deposits within the breast tissue, which look like small white spots on the films. They may or may not be caused by cancer. There are 2 types of calcifications:
A mass, which may occur with or without calcifications, is another important change seen on mammograms. Masses can be many things, including cysts (non-cancerous, fluid-filled sacs) and non-cancerous solid tumors (such as fibroadenomas), but they could also be cancer. Masses that are not cysts usually need to be biopsied.
Having your previous mammograms available for the radiologist is very important. They can be helpful to show that a mass or calcification has not changed for many years. This would mean that it is probably a benign condition and a biopsy is not needed.
Limitations of mammograms
A mammogram cannot prove that an abnormal area is cancer. To confirm whether cancer is present, a small amount of tissue must be removed and looked at under a microscope. This procedure, called a biopsy, is described here.
You should also be aware that mammograms are done to find breast cancer that cannot be felt. If you have a breast lump, you should have it checked by your doctor and consider having it biopsied even if your mammogram result is normal.
For some women, such as those with breast implants, additional pictures may be needed. 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.
Mammograms are not perfect at finding breast cancer. They do not work as well in younger women, usually because their breasts are dense, and can hide a tumor. This may also be true for pregnant women and women who are breast-feeding. Since most breast cancers occur in older women, this is usually not a major concern.
However, this can be a problem for young women who are at high risk for breast cancer (due to gene mutations, a strong family history of breast cancer, or other factors) because they often develop breast cancer at a younger age. For this reason, the American Cancer Society now recommends MRI scans in addition to mammograms for screening in these women. (MRI scans are described below.)
More information on these tests is available here and the separate American Cancer Society document, Mammograms and Other Breast Imaging Procedures.
What to expect when you have a mammogram
If you are a woman aged 40 or over, you should get a mammogram every year. You can schedule the next one while you're at the facility and/or request a reminder.
Tips for having a mammogram
The following are useful suggestions for making sure that you will receive a quality mammogram:
Help with mammogram costs
Medicare, Medicaid, and most private health insurance plans cover mammogram costs or a percentage of them. Low-cost mammograms are available in most communities. Call 1-800-227-2345 for information about facilities in your area.
Breast cancer screening is now more available to medically underserved women through the National Breast and Cervical Cancer Early Detection Program (NBCCEDP). This program provides breast and cervical cancer early detection testing to women without health insurance for free or at very low cost. Although the program is administered within each state, the Centers for Disease Control and Prevention (CDC) provide matching funds and support to each state program. Each state's Department of Health has information on how to contact the nearest program.
The program is only designed to provide screening. But if a cancer is discovered, it will cover further diagnostic testing and a surgical consultation.
The Breast and Cervical Cancer Prevention and Treatment Act gives states Medicaid funds to pay for treating breast and cervical cancers that are detected through the NBCCEDP. This helps women focus their energies on fighting their disease, instead of worrying about how to pay for treatment. All states participate in this program.
To learn more about these programs, please contact the CDC at 1-800-CDC INFO (1-800-232-4636) or online.
Clinical breast exam
A clinical breast exam (CBE) is an exam of your breasts by a health care professional, such as a doctor, nurse practitioner, nurse, or doctor's assistant. For this exam, you undress from the waist up. The health care professional will first look at your breasts for abnormalities in size or shape, or changes in the skin of the breasts or nipple. Then, using the pads of the fingers, the examiner will gently feel (palpate) your breasts.
Special attention will be given to the shape and texture of the breasts, location of any lumps, and whether such lumps are attached to the skin or to deeper tissues. The area under both arms will also be examined.
The CBE is a good time for women who don't know how to examine their breasts to learn the proper technique from their health care professionals. Ask your doctor or nurse to teach you and watch your technique.
Breast awareness and self exam
Beginning in their 20s, women should be told about the benefits and limitations of breast self-exam (BSE). Women should know how their breasts normally look and feel and report any new breast changes to a health professional as soon as they are found. Finding a breast change does not necessarily mean there is a cancer.
A woman can notice changes by being aware of how her breasts normally look and feel and by feeling her breasts for changes (breast awareness), or by choosing to use a step-by-step approach (see below) and using a specific schedule to examine her breasts.
If you choose to do BSE, the information below is a step-by-step approach for the exam. The best time for a woman to examine her breasts is when the breasts are not tender or swollen. Women who examine their breasts should have their technique reviewed during their periodic health exams by their health care professional.
Women with breast implants can do BSE, too. It may be helpful to have the surgeon help identify the edges of the implant so that you know what you are feeling. There is some thought that the implants push out the breast tissue and may actually make it easier to examine. Women who are pregnant or breast-feeding can also choose to examine their breasts regularly.
It is acceptable for women to choose not to do BSE or to do BSE once in a while. Women who choose not to do BSE should still be aware of the normal look and feel of their breasts and report any changes to their doctor right away.
How to examine your breasts
Magnetic resonance imaging (MRI)
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, because although it is a sensitive test, it may still miss some cancers that mammograms would detect.
MRI scans use magnets and radio waves (instead of x-rays) to produce very detailed, cross-sectional images of the body. The most useful MRI exams for breast imaging use a contrast material (gadolinium) that is injected into a vein in the arm before or during the exam. This improves the ability of the MRI to clearly show breast tissue details.
Although MRI is more sensitive in detecting cancers than mammograms, it also has a higher false-positive rate (where the test finds something that turns out not to be cancer), which results in more recalls and biopsies. This is why it is not recommended as a screening test for women at average risk of breast cancer, as it would result in unneeded biopsies and other tests in a large portion of these women.
Just as mammography uses x-ray machines that are specially designed to image the breasts, breast MRI also requires special equipment. Breast MRI machines produce higher quality images than MRI machines designed for head, chest, or abdominal scanning. However, many hospitals and imaging centers do not have dedicated breast MRI equipment available. It is important that screening MRIs be done at facilities that can perform an MRI-guided breast biopsy. Otherwise, the entire scan will need to be repeated at another facility when the biopsy is done.
MRI is more expensive than mammography. Most major insurance companies will likely pay for these screening tests if a woman can be shown to be at high risk, but it's not yet clear if all companies will do so. At this time there are concerns about costs of and limited access to high-quality MRI breast screening services for women at high risk of breast cancer.
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