Mammography : Benefits and Risks (ZT)

By Mayo Clinic staff

Mammography is X-ray imaging of your breasts designed to detect tumors and 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.

When to 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 26 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 magnetic resonance imaging (MRI) in combination with mammography 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 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	Optional; consider performing on a regular (such as monthly) 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

Risk and limits

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

• Mammography exposes you to low-dose radiation. The dosage is very low, though, 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. Always tell your physician if you've noticed a change in your breast, especially if your mammogram is interpreted as normal.
• 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, about 10 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 one in five 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 shows areas of concern that may be cancer, your doctor will likely recommend a breast biopsy. A biopsy is a procedure to remove a piece of tissue or a sample of cells from your body so that it can be analyzed by a pathologist — a doctor who specializes in examining body tissues. If your mammogram or biopsy show that you have breast cancer, you and your doctor can discuss the best course of treatment.

If the breast biopsy results are normal or reveal a benign breast condition, talk with your doctor to be sure that the radiologist and the pathologist drew the same conclusions from your mammogram and your biopsy. If they have interpreted your test results differently, you may need further testing