Mammography

Mammography is the most common method for detecting abnormalities in the breast. This screening technique is an x-ray that uses very low levels of radiation (see The Mammography Procedure). It can find 85%-90% of breast cancers. Mammography makes it possible to see tiny cancers that may measure as little as half a centimeter (about one-fifth of an inch). Generally, a lump can't be felt until it's at least twice that size. The abnormalities that show up on a mammogram may be benign or malignant.

Research shows that annual screening mammography performed on large populations of women who otherwise have no breast complaints may save lives in women ages 50 and older and suggests that it possibly reduces mortality in women ages 40-49. The American Cancer Society and other medical groups recommend that women have an annual mammogram starting at age 40. Women who are at high risk for breast cancer because of a family history or other factors may begin screening at an earlier age. The downside of mammography is that it has increased the number of surgical biopsies in women who do not have breast cancer, and may increase a patient's anxiety level. As with any surgical procedure, complications may occur following a biopsy.

On a mammogram, the structures inside your breast appear in shades ranging from white to black. The white areas are mainly milk ducts. The hazy gray and black areas are fat tissue. Abnormalities appear as white spots of two types: densities or calcifications (see What the Radiologist Sees).

Densities
These abnormalities appear as light spots on the mammogram. If a density appears on a mammogram, the radiologist will examine it with two or more different mammographic views. A density may or may not indicate cancer. A density with a starburst shape (arms radiating outward from the center) is called "spiculated" and often indicates cancer. Noncancerous densities usually appear as a spot with a smooth outline and no arms radiating outward. If a density appears on a mammogram, the next step is usually a breast ultrasound (see Breast Ultrasound).

Calcifications
These abnormalities appear as tiny, sand-grain-sized bright white dots. Most calcifications are benign. Benign calcifications are usually scattered randomly through both breasts, almost like a snowstorm. Or, benign calcifications may be clustered in a small space and are usually similar in size and may be coarse in appearance. If the calcifications appear to be benign, you and your doctors can monitor any further changes with yearly mammograms. Calcifications that appear as tiny dots of different sizes and shapes (pleomorphic) in a line (linearly arranged) are likely inside a duct and generally indicate cancer. More than 70% of suspicious indications that are biopsied turn out to be benign.

Assessing the mammogram
Radiologists use standard terminology for classifying the findings of a mammogram. The radiologist will use numbered categories to refer to the shape and margins of a mass, the appearance and distribution of calcifications, and the radiologist's level of suspicion that the abnormality represents a breast cancer. Such a classification system provides a common language for communication between radiologists, clinicians, and the women having the mammograms, regardless of where the procedure has been done. The categories were developed by the Breast Imaging Reporting and Data System. It is very likely that the letter you receive from either the radiologist or your physician who ordered the mammogram will include the BI-RADS scoring system in their report to you. (see BI-RADS Assessment Categories).

Next >> Breast Ultrasound

In This Article:
Detecting Breast Cancer
Breast Self-Exam and Clinical Exam
Mammography
Breast Ultrasound
Magnetic Resonance Imaging (MRI)
Breast Ductogram
Breast Biopsy

From the Harvard Health Publications Special Health Report, Breast Cancer: Strategies for Living. Copyright 2004 by the President and Fellows of Harvard College. Illustrations by Harriet Greenfield, M.A., and Jesse Tarantino. All rights reserved. Used with permission of StayWell. Harvard Medical School does not endorse products.
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