One of the best ways a woman age 40 or older can defend herself against breast cancer is to have yearly screening mammograms.

What is a mammogram?

A mammogram is a special type of x-ray that makes a picture of the inside of the breast. Mammograms use radiation, but the amount is very low. The potential harm from this small amount of radiation is very small and far outweighed by the potential benefit.

Mammograms can be done in a radiology facility, a hospital or clinic, or a doctor's office. There are 2 kinds of mammograms: screening mammograms and diagnostic mammograms.

A screening mammogram is an x-ray of the breast of a woman who has no breast symptoms or problems. Women over 40 should get screening mammograms every year to look for changes in their breast tissue. Because most breast cancers do not cause symptoms, a screening mammogram may be the best way for most women to find cancers early, when they are small, have not spread, and are most treatable.

A diagnostic mammogram is used to find breast disease in women who have symptoms or areas of change on their screening mammogram. Diagnostic mammograms help the doctor learn more about breast masses or the cause of other breast symptoms.

Screening mammograms are usually not very useful for women younger than 40. This is because breast tissue in most younger women is too dense to give a good, clear x-ray image. Women who have a family history of breast cancer, a genetic tendency, or certain other factors may need to start testing before age 40 and be screened with an MRI along with the mammogram. Talk with your doctor about your history and the screening tests and schedule that are best for you.

Mammogram results

When doctors look at mammogram results, they compare the x-rays from previous mammograms and look for differences between the breast images. Sometimes the x-ray will show tiny bits of calcium in the breast called microcalcifications. Most microcalcifications are harmless, but in some cases, they can be a sign of cancer or a pre-cancerous condition. The doctor looks at the shape and arrangement of the microcalcifications to decide if a biopsy is needed. Sometimes, the doctor may see an area of the breast that looks a little different but not enough to report the mammogram as abnormal. When this happens, the doctor may ask that the mammogram be repeated in about 6 months.

The mammogram may also show the presence of a mass, or suspicious-looking area of tissue. Masses are not a sure sign of cancer. The doctor will look at the size, shape, and margins (edges) of the mass to figure out the likelihood of cancer. More testing may be needed to find out if it is cancer.

Mammograms are the best way for most women to check for cancer in its early stages, but a mammogram alone cannot prove that a suspicious area is cancer. If cancer is suspected, more testing will be needed.

Remember:

• Only 2 to 4 mammograms in 1,000 lead to a diagnosis of cancer.
• About 10% of women will need to have more tests or another mammogram after the first one is taken. Don't be alarmed if this happens to you. Sometimes this happens if there is a technical problem with the x-ray film, or if the film was hard to read.
• Only 8% to 10% of the women who need repeat mammograms will need a biopsy, and 80% of those biopsies will not be cancer.
• Breast cancer can be cured, especially if it's caught early enough.