Mammography: X-ray exam to detect breast cancer

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Mammography: X-ray exam to detect breast cancer

Mammography is an X-ray exam designed to detect breast cancer at an early stage.

Breast cancer is the second-leading cause of death from cancer among women in the United States, following lung cancer. In 2005, an estimated 211,000 new cases of breast cancer will be diagnosed and more than 40,000 women will die of the disease.

However, great strides in early detection and improved treatment have decreased breast cancer deaths. Mammography plays a key role in early detection. Through mammography, your doctor can detect breast cancer nearly one to three years before you might actually feel a lump in your breast.

What is mammography?

Mammography is X-ray imaging of your breasts designed to detect tumors or other abnormalities. Mammography can be used either for screening or for diagnostic purposes in evaluating a breast lump.

Screening mammography
Screening mammography is used to detect breast changes in women who have no signs or symptoms or observable breast abnormalities. The goal is to detect cancer before any clinical signs are noticeable. This usually requires at least two mammograms from different angles of each breast.

Diagnostic mammography
Diagnostic mammography is used to investigate suspicious breast changes such as a breast lump, breast pain, an unusual skin appearance, nipple thickening or nipple discharge. It's also used to evaluate abnormal findings on a screening mammogram. Additional images can be made from other angles or focus on areas of concern at higher magnification.

At what age should you begin screening mammography?

Experts don't agree on the frequency with which women should have regular mammograms. The American Cancer Society recommends that women age 40 and older have a screening mammogram every year, while the National Cancer Institute recommends that women age 40 and older have one every one to two years.

Your doctor can recommend a screening mammography schedule for you. Some general guidelines for when to begin screening mammography include:

  • If you're age 20 to 39 and at average risk of breast cancer, you don't need screening mammograms yet.
  • If you're age 20 to 39 and at high risk of breast cancer, you may benefit by beginning screening mammograms. Talk to your doctor for an individualized program. Your doctor may also recommend other screening methods, such as whole breast ultrasound or magnetic resonance imaging in combination with mammography. Your doctor may recommend these screening options based on your risk factors and your degree of breast density.
  • If you're age 40 or older, you should have screening mammograms every one to two years, depending on your doctor's recommendation. This is true for women both at average risk and at high risk of breast cancer.

Because breast cancer screening involves more than just mammography, here are some additional recommendations on clinical breast exams and breast self-exams.

Breast cancer screening guidelines
Age Breast cancer risk Mammograms Clinical breast exams Breast self-exams
20 to 39 Average Not needed Every three years Consider performing on a regular basis to increase your breast health awareness.
20 to 39 High May be needed. Talk with your doctor. Every year
40 or older Average to high Every one to two years Every year

How do you prepare for mammography?

Schedule the test for a time when your breasts are least likely to be tender. They're often least tender during the week after your menstrual period. Your breasts are most likely to be tender the week before and the week during your period.

A few weeks before the test
If you're going to a new facility for your mammogram, gather any prior mammograms and bring them with you to your appointment for comparison. It's important to bring the original mammogram films, not copies, and accompanying reports.

The day of the test
Don't apply deodorants, antiperspirants, powders, lotions, creams or perfumes under your arms or on your breasts. Metallic particles in powders and deodorants could be visible on your mammogram and cause confusion.

Taking an over-the-counter pain medication, such as aspirin, acetaminophen (Tylenol, others) or ibuprofen (Advil, Motrin, others), about an hour before your mammogram might ease the discomfort of the test.

How is mammography done?

At the testing facility, you're given a gown and asked to remove neck jewelry and clothing from the waist up. It's a good idea to wear a two-piece outfit that day.

For the procedure itself, you stand in front of an X-ray machine specially designed for mammography. The technician places one of your breasts on a platform that holds the X-ray film and raises or lowers the platform to match your height. The technician helps you position your head, arms and torso to allow an unobstructed view of your breast.

photograph of technician positioning woman for mammography
A technician positions a woman for mammography.

Your breast is gradually pressed against the platform by a clear plastic plate. Pressure is applied for a few seconds to spread out the breast tissue. The pressure isn't harmful, but you may find it uncomfortable or even painful. If you have too much discomfort, inform the technician.

Your breast must be compressed to even out its thickness and permit the X-rays to penetrate the breast tissue. The pressure also holds your breast still to decrease blurring from movement and minimizes the dose of radiation needed. During the brief X-ray exposure, you'll be asked to stand still and hold your breath.

After images are made of both your breasts, you may be asked to wait while the technician checks the quality of the images. If the views are inadequate for technical reasons, you may have to repeat part of the test. The entire procedure usually takes less than 30 minutes. Afterward, you may dress and resume normal activity.

Results of mammography

Mammography produces mammograms — black-and-white images of your breast tissue on X-ray film. A radiologist interprets the images and sends a written report of the findings to your doctor.

The radiologist looks for evidence of cancer or noncancerous (benign) conditions that may require further testing, follow-up or treatment.

Possible findings include:

  • Calcium deposits (calcifications) in ducts and other tissues
  • Masses or lumps
  • Distorted tissues
  • Dense areas appearing in only one breast
  • Dense areas that have appeared since your last mammogram

Calcifications can be the result of cell secretions, cell debris, inflammation, trauma, previous radiation or foreign bodies. Tiny, irregular deposits called microcalcifications may be associated with cancer. Larger, coarser deposits called macrocalcifications may be caused by a benign condition such as fibroadenoma — a common noncancerous tumor of the female breast — or by aging or injury. Most breast calcifications are benign, but if calcifications appear worrisome, the radiologist might order additional diagnostic images with magnification.

Breast calcifications on mammogram

Breast calcifications on mammogram

Calcifications are small calcium deposits in the breast that show up as white spots on a mammogram. Round, well-defined, larger calcifications (left column) are more likely to be noncancerous (benign). Tight clusters of tiny, irregularly shaped calcifications (right column) may indicate cancer.

Risks and limitations of mammography

Mammography isn't foolproof. It does have some limitations and potential risks:

  • Mammography exposes you to low-dose radiation. But the dosage is very low, and for women over age 40, the benefits of regular mammography outweigh the risks posed by this amount of radiation.
  • Mammograms aren't always accurate. The accuracy of the procedure depends in part on the quality of the film, the technique used and the experience and skill of the radiologist. Other factors — such as your age and breast density — may result in false-negative or false-positive mammograms.
  • Mammograms in younger women can be difficult to interpret. The breasts of younger women contain more glands and ligaments than do those of older women, resulting in dense breast tissue that can obscure signs of cancer. With age, breast tissue becomes fattier and has fewer glands, making it easier to interpret the mammograms to detect changes.
  • Having a mammogram may lead to additional testing. Among women of all ages, 5 percent to 15 percent of mammograms require additional testing. However, most abnormal findings aren't cancer. If you're told that your mammogram is abnormal, make sure that the radiologist has compared your current mammogram with any previous mammograms.
  • Screening mammography can't detect all cancers. Some cancers detected by physical examination may not be seen on the mammogram. A cancer may be too small or may be in an area that is difficult to view by mammography, such as your armpit. Mammograms can miss about 10 percent to 15 percent of cancers in women. And that number might be higher in women who have a greater breast density.
  • Not all of the tumors found by mammography can be cured. Certain types of cancers are aggressive, grow rapidly and spread early to other parts of your body.

If your mammogram does show that you have breast cancer, you and your doctor can discuss treatment options and decide on the best course of treatment for you.

Emerging technologies

New methods for viewing and interpreting mammograms are being developed. Promising technology may improve radiologists' ability to more accurately detect breast cancer in its earliest stages. Among newer methods being explored are:

  • Digital mammography. With digital mammography, you undergo the same X-ray procedure as with regular mammography, except that the images are stored on a computer instead of on X-ray film. Such images can be stored and retrieved electronically, and the radiologist can adjust images to better evaluate possible areas of concern, which may help in detecting subtle differences in the breast tissue.

    Previous studies comparing digital mammography with traditional film mammography have shown them to be equivalent for breast cancer detection. However, a study published in the September 15, 2005 issue of the "New England Journal of Medicine" has found digital mammography to be better than traditional mammography at detecting breast cancer in premenopausal and perimenopausal women and women with dense breasts, such as younger women. Because of the newness of the procedure, though, digital mammography may be difficult to find at a medical facility near you.

  • Computer-aided detection. This method also uses computers to enhance mammograms. After the images of the breast are reviewed by the radiologist, they're processed by a computer that has been programmed to recognize certain features. Possible suspicious areas are highlighted for the radiologist to re-review and compare with prior mammograms. This technology has been shown to improve the accuracy of screening mammograms. The computer also highlights many areas that are not cancer. The interpreting radiologist decides if additional evaluation is indicated. Computer-aided detection is in use at some mammography facilities today.

Regardless of whether your mammography facility uses digital mammography or computer-aided detection, you can expect the general procedure to remain the same when you get your next mammogram.

Last Updated: 11/30/2005
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