Mammography (ma-MAH-gruh-fee) is a screening tool that uses X-rays to create an image of the breast. These images, called mammograms (MAM-o-grams), are used to find signs of breast cancer such as tumors, small clusters of calcium (microcalcifications) and abnormal changes in the skin. Mammography is the best screening tool used today for breast cancer. It can find cancers at an early stage, when they are small and most responsive to treatment. Mammograms can be done in certified radiology centers, mammography clinics, hospital radiology departments, mobile vans and some physicians’ offices.
Right before the procedure, you will undress from the waist up, so it is a good idea to wear a shirt that you can remove easily. Avoid using deodorants, antiperspirants, perfumes, powders or lotions on the day of the exam. Ingredients in these products can show up on a mammogram and look like calcifications.
Getting a mammogram takes about 15 minutes. During the procedure, each breast is pressed between two plates, and an X-ray image is made. Two views are taken, one from top to bottom and one from side to side. For some women, the pressure can be uncomfortable, but it only lasts a few seconds. Taking acetaminophen (Tylenol) or ibuprofen (Advil, Motrin) about an hour before the exam may help. If you have concerns, talk to your health care provider about other ways to help ease discomfort (or anxiety) during a mammogram. And, before the exam, let your radiation technologist know you are anxious. This may help her understand your concern and work with you to get good images while being sensitive to your needs.
Standard (film) mammography versus digital mammography
The X-ray images of the breast are captured on film (standard mammography) or stored directly onto a computer (digital mammography). Film and digital mammography are similar in their ability to detect cancer [1-3]. However, digital images can be viewed in different ways on a computer. They can be lightened or darkened, and certain sections can be enlarged and examined more closely. The ability to control digital images on a computer makes digital mammography more accurate for some women. The large, multi-center Digital Mammographic Imaging Screening Trial (DMIST) found that digital mammography was better at detecting cancer in women who fell into one or more of the following groups [3]:
- Women who are premenopausal or peri-menopausal
- Women who are under age 50
- Women who have dense breast tissue
As digital mammography images are stored on a computer, they can be sent via email to another radiologist for review. However, digital mammography is more costly than film mammography and it does not appear to offer any benefit for women who do not fall in one of the above categories. And, although digital mammography has become more common, it is not available at all mammography centers. Insurance coverage for digital mammography varies, so it is important to talk to your provider before your screening.
Computer-assisted detection (CAD)
After the procedure, radiologists with advanced mammography training read the film or digital images, looking for signs of breast cancer. Computer-assisted detection (CAD) was developed to help radiologists find suspicious areas on a digital mammogram or a standard mammogram converted to a digital image. In CAD, software analyzes the images and highlights areas of concern that should be looked at further. Although some studies suggest CAD may improve cancer detection, the largest study to date showed CAD actually reduced the accuracy of interpretation of mammograms compared to regular visual reading [4-6]. Moreover, the authors found CAD led to an increase in false-positive results [6]. (Find more on false-positive results.) Therefore, the benefit of CAD needs further study.
Findings
Images on mammograms appear in shades of black, gray and white, depending on the density of the tissue. Very dense tissue, like bone shows up as white on an X-ray. Fat looks dark gray on an X-ray. Cancerous tumors and some benign conditions are denser than fat and appear a lighter shade of gray or white on an X-ray image.
Normal dense breast tissue can look light gray on a mammogram, which can make mammograms harder to interpret in younger women, who tend to have denser breasts. After menopause, breast density decreases, making it easier to read the mammograms of older women. Some younger women may have lower breast density after an oophorectomy (removal of the ovaries) or hysterectomy. Older women who use postmenopausal hormones often have higher breast density until they stop using hormones. For women with dense breast tissue, digital mammography is more accurate than standard mammography. Learn more about breast density in the Risk Factors and Prevention section.
Some common benign breast conditions, such as cysts and fibroadenomas, generally show up on mammograms as round or oval patches with distinct borders. These well-defined borders help radiologists see where the benign abnormal tissue ends and the surrounding normal tissue begins. Learn more on benign breast conditions.
In contrast, cancer cells do not stay within the clear borders that separate the cells from surrounding tissue. Instead, they invade the surrounding tissue. When this occurs, the core cancer cells appear as a light patch on a mammogram. The cells that have spread out into the normal tissue have a fuzzy or spiky appearance along their outer edge (called spiculated).
Bits of calcium (calcifications), which can show up on mammograms as small, bright white spots, can be a sign of breast cancer. Calcifications are common and appear on about half of all mammograms [7]. Most calcifications are benign. However, certain patterns of calcifications are suspicious and need more testing. Tight clusters or lines of tiny calcifications (microcalcifications) can be a sign of cancer. Learn more about follow-up after an abnormal mammogram.
Some centers may give you the results of your mammogram at the time of your screening. However, depending on the center, it may take up to two weeks to get the results. If you do not receive the results within this time, you should follow up with your health care provider or the mammography center. Do not assume that the results were normal just because you haven’t gotten a report.
Breast implants and mammography
Mammography is a safe and effective screening tool for women who have breast implants. However, if you have implants, it is important to tell the technologist before the procedure. Special adjustment of the mammography machine is required to avoid full compression of the implant. In addition, special positioning of the breast will be required. Four views will be taken instead of the standard two views of each breast. If possible, choose a center with technologists and radiologists who are experienced in mammography for women with breast implants.
Breastfeeding and mammography
While you are breastfeeding, the tissue in your breasts can appear dense on a mammogram, which makes it hard to read. For this reason, it is often best to wait until you stop breastfeeding to get a routine screening mammogram. However, you should discuss the best timing of your mammogram with your health care provider if you are due for screening. If you have any concerns about your breasts (such as finding a lump or noting any change), talk to your health care provider right away.
Low-cost or free mammography
Most insurance companies cover the cost of mammograms. And, in many areas of the country, low-cost or free mammograms are offered as part of the National Breast and Cervical Cancer Control Program or through community organizations, such as the YWCA. Komen Affiliates fund breast cancer education, screening and treatment projects for those who need it most. Find an Affiliate in your area to learn what resources are available. Or, call our breast care helpline at 1-877 GO KOMEN (1-877-465-6636) to find low cost options or a certified radiology center in your area. Also, in October each year, during Breast Cancer Awareness Month, many imaging centers offer mammography at reduced rates. For a list of certified radiology centers, visit the FDA Web site (http://www.fda.gov/cdrh/mammography/certified.html).
Physical disabilities and breast cancer screening
Research shows that women with physical disabilities tend to have mammograms less often than women without such limitations [8,9]. While many factors cause this disparity, one common reason is lack of access [8,10]. Many mammography facilities (especially mobile ones) simply aren't designed for women who have trouble getting around. One solution is to call the certified mammography centers in your area until you find one that meets your needs. Partnering with your health care provider in your search can help things go more smoothly and may make things easier for other disabled women as well.
Disabled women themselves know best how to improve facilities, patient- provider interactions and medical equipment. So, let your voice be heard by the larger community. If access to health care for the disabled isn't as good as it could be in your area, be sure to let your local medical centers, health insurance providers and elected officials know. One in five U.S. women has some level of physical disability, making a powerful group to lobby for change [11].
Trends in use of screening mammography
After mammography was shown to be an effective breast cancer screening tool in the late 1980's, use of screening mammography in the U.S. rapidly increased. In 2005, 68 percent of white women, 65 percent of African American women, and 60 percent of Hispanic/Latino women 40 years and older reported having a recent mammogram [12]. This is a slight decline from 2000 rates [12,13]. The cause(s) for this decline are not yet known. There is concern that a decrease in screening mammography may lead to an increase in breast cancer mortality because fewer cancers will be found at an early stage when they are most treatable. Learn more about race and ethnicity issues in screening.
Radiation exposure during mammography
A woman is exposed to some radiation during a mammogram. While the radiation exposure during mammography can increase the risk of breast cancer, this increase in risk is very small [14]. Studies show that the benefits of mammography outweigh the risks from radiation exposure for women ages 40 to 50. And, for women ages 50 and older, these benefits are far greater [15].
Updated 10/28/09
