The Who, What, Where, When and Sometimes, Why.

Accuracy of Mammograms

Mammography is good at finding breast cancer, especially in women ages 50 and older.

Overall, the sensitivity of mammography is about 87 percent [31]. This means mammography correctly identifies about 87 percent of women who truly have breast cancer.

Sensitivity is higher in women over 50 than in younger women [2]. It’s also higher in women with fatty breasts than in women with dense breasts [2].

Learn more about sensitivity.

False positive results

One downside of missing so few cancers is false positive results (when a mammogram shows there’s cancer when in fact, there’s no cancer in the breast).

The more mammograms a woman has, the more likely it is she will have a false positive result that needs follow-up tests

The chance of having a false positive result after one mammogram ranges from 7-12 percent, depending on your age (younger women are more likely to have a false positive results) [28]. After 10 yearly mammograms, the chance of having a false positive is about 50-60 percent [19-21].

The chance of a false positive result is higher among younger women and women with dense breasts [32]. (Most women younger than 50 have dense breasts, so there’s overlap among these groups.)

A false positive result can cause fear and worry [21,33-34]. Some women may still have these feelings a year later [33].

If you’re called back to check an abnormal finding on your mammogram, try not to panic. False positive results are common. Most women who are called back don’t have breast cancer [19].

Menopausal hormone therapy and mammography

What is menopausal hormone therapy?

Some women take menopausal hormone therapy (MHT) to relieve menopausal symptoms, such as hot flashes. MHT is also known as postmenopausal hormone therapy and hormone replacement therapy (HRT).

The use of MHT increases breast cancer risk [35]. So, the U.S. Food and Drug Administration (FDA) recommends women use only the lowest dose that eases symptoms for the shortest time needed [36].

Learn more about MHT and breast cancer risk.

How does MHT use affect mammogram findings?

There are 2 main types of MHT used today: estrogen plus progestin and estrogen alone.

Results from the Women’s Health Initiative showed women who took estrogen plus progestin (but not women who took estrogen alone) had breast cancers found at more advanced stages than those found in women who didn’t take MHT [37-38].

Women who took either type of MHT had higher breast density and more abnormal mammograms (not explained by the higher breast density) that needed follow-up tests [37-41].

Experience of the radiologist matters

To get accurate mammogram findings, you need a high-quality image and a good reading of that image.

The training and experience of the radiologist who reads your mammogram may improve their ability to interpret the image.

Radiologists who read a lot of mammograms are generally better able to interpret the images than radiologists who don’t read them often [42-44].

High-volume hospitals and mammography centers

A high-volume mammography center may help you feel assured your mammogram will be read correctly. However, most lower-volume, certified mammography centers also provide quality screening [45].

To find a certified mammography center in your area, visit the FDA website (www.fda.gov).

Can mammography miss breast cancer?

Although mammography is the most effective breast cancer screening tool today for most women, it’s not perfect.

Mammography misses about 13 percent of breast cancers [31]. Depending on certain factors (such as breast density), mammography may miss more breast cancers [46].

Some breast cancers are harder for mammography to detect than others.

For example, mammography is better at finding breast cancers that begin in the milk ducts (invasive ductal carcinoma) than breast cancer that begin in the lobules (invasive lobular carcinoma) [47]. Invasive lobular carcinomas don’t always appear as a distinct mass on a mammogram, so they are harder to find.

Other imaging tests in combination with mammography are under study for use in routine breast cancer screening.

Learn about emerging areas in early detection.