Mammography: Benefits, Risks, What You Need to Know

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Mammograms don’t prevent breast cancer, but they can save lives by finding breast cancer as early as possible. For example, mammograms have been shown to lower the risk of dying from breast cancer by 35% in women over the age of 50. In women between ages 40 and 50, the risk reduction appears to be somewhat less.

The value of screening mammograms was questioned in November 2009 when the U.S. Preventive Services Task Force recommended that routine screening mammograms for women with an average risk of breast cancer should start at age 50 instead of age 40. The recommended changes were very controversial and were not universally adopted.

Since that time, the American Medical Association, the American College of Obstetricians and Gynecologists, the American College of Radiology, the American Cancer Society, the National Cancer Institute, and the National Comprehensive Cancer Network all have issued guidelines saying that all women should be eligible for screening mammograms starting at age 40.

Finding breast cancers early with mammography has also meant that many more women being treated for breast cancer are able to keep their breasts. When caught early, localized cancers can be removed without resorting to breast removal (mastectomy).

The main risk of mammograms is that they aren’t perfect. Normal breast tissue can hide a breast cancer so that it doesn't show up on the mammogram. This is called a false negative. And mammography can identify an abnormality that looks like a cancer, but turns out to be normal. This "false alarm" is called a false positive. Besides worrying about being diagnosed with breast cancer, a false positive means more tests and follow-up visits, which can be stressful. To make up for these limitations, more than mammography is often needed. Women also need to practice breast self-examination, get regular breast examinations by an experienced health care professional, and, in some cases, also get another form of breast imaging, such as breast MRI or ultrasound.

Some women wonder about the risks of radiation exposure due to mammography. Modern-day mammography only involves a tiny amount of radiation — even less than a standard chest X-ray.

Five important things to know about mammograms

  1. They can save your life. Finding breast cancer early reduces your risk of dying from the disease by 25-30% or more. Women should begin having mammograms yearly at age 40, or earlier if they're at high risk.
  2. Don't be afraid. Mammography is a fast procedure (about 20 minutes), and discomfort is minimal for most women. The procedure is safe: there's only a very tiny amount of radiation exposure from a mammogram. To relieve the anxiety of waiting for results, go to a center that will give you results before you leave.
  3. Get the best quality you can. If you have dense breasts or are under age 50, try to get a digital mammogram. A digital mammogram is recorded onto a computer so that doctors can enlarge certain sections to look at them more closely.

    Other tips:
    • Bring your past mammogram films/results with you. If you’ve been to the same facility before, make sure your past results are available to whoever is reading the study.
    • Once you find a facility you have confidence in, try to go there every year, so that your mammograms can be compared from year to year.
    • Have more than one radiologist read your study, if your insurance covers this.
    • Ask if your center has CAD — computer-aided detection — a tool that assists the radiologist in finding any areas of concern that need further attention.
    • If you’ve been referred for a mammogram because of a suspicious lump or a finding on another test, make sure your doctor includes a detailed note as to why the mammogram has been ordered. For example, if the doctor felt a lump in the upper portion of the breast, closer to the underarm, the note might say, “palpable mass in the upper outer quadrant, left breast, rule out abnormality.” Be prepared to talk about previous unusual findings or symptoms with the technologist who performs the mammogram.
    • Work with your doctor to compare your mammogram results with any other tests you may have had done, such as ultrasound or MRI.
    • On the day of the exam, wear a skirt or pants, rather than a dress, since you’ll need to remove your top for the test. Don’t wear deodorant or antiperspirant, since these can show up on the film and interfere with the test results.
    • Avoid scheduling your mammogram at a time when your breasts are swollen or tender, such as right before your period.
    • Discuss your family history of breast and other cancers — from both your mother's AND father’s side — with your doctor.
    • If you don’t receive any results within 30 days, call your doctor or testing facility to ask for the results.
  4. Mammography is our most powerful breast cancer detection tool. However, mammograms can still miss 20% of breast cancers that are simply not visible using this technique. Other important tools — such as breast self-exam, clinical breast examination, and possibly ultrasound or MRI — can and should be used as complementary tools, but there are no substitutes or replacements for a mammogram.
  5. An unusual result requiring further testing does not always mean you have breast cancer. According to the American Cancer Society, about 10% of women (1 in 10) who have a mammogram will require more tests. Only 8-10% of these women will need a biopsy, and about 80% of these biopsies will turn out not to be cancer. It’s normal to worry if you get called back for more testing, but try not to assume the worst until you have more information.

There have been myths about mammograms that you might have heard about on TV or the Internet. One of these myths is that the pressure from mammograms on a malignant tumor can break it open and cause it to metastasize. There is absolutely no evidence for this claim. In fact, not getting a mammogram or not exerting enough compression during a mammogram will increase the risk of a delayed diagnosis, resulting in a higher risk of metastatic disease.

When to get a mammogram

There's a lot of confusion out there about when and how often to get a mammogram. For now, the recommendation is that women get a mammogram once a year, beginning at age 40. If you're at high risk for breast cancer, with a strong family history of breast or ovarian cancer, or have had radiation treatment to the chest in the past, it's recommended that you start having annual mammograms at a younger age (often beginning around age 30). This, however, is something that you should discuss with your health care provider.

Expert Quote

"Mammography plays a critical part in diagnosing breast cancer. In the past, we'd often find that a woman had breast cancer when she came in with a lump. Today, the cancers radiologists find on mammography are usually detected early, before they can be felt by the patient, are smaller than cancers felt by patients, and have much lower levels of lymph node involvement."

-- Susan Greenstein Orel, M.D.

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