How to Read & Decode Your Mammogram Report

Annual screening mammograms are our best opportunity to find breast cancer early.

The American College of Radiology recommends breast cancer screening with mammography starting at age 40 for women at average risk.

Understanding BI-RADS Scores

The American College of Radiology developed the Breast Imaging Report and Data System (BI-RADS) so radiologists can communicate clearly and consistently about what your mammogram shows.

• Category 0: Incomplete. The doctor needs more pictures or older scans to compare
• Category 1: Negative. Normal mammogram.
• Category 2: Benign. Mammogram may note harmless things like cysts or old scars.
• Category 3: Probably Benign. The finding has less than 2% chance of cancer but needs follow up in six to 12 months.
• Category 4: Suspicious. Findings in question need biopsy/tissue sample for diagnosis.
• Category 5: Highly Suggestive of Malignancy. Findings with high chance (95% or more) of being cancer. Biopsy is strongly urged.
• Category 6: Known Cancer.

Breast Density Levels

Your mammogram report also includes information on breast density. Breast tissue consists of two types: fatty and fibroglandular. If more than 50% of your breast is made of fibroglandular tissue, then your breasts are classified as dense.

Breast density isn’t abnormal, but it does make it harder to read your mammogram. On an X-ray mammogram, fatty breast tissue appears gray, while both dense breast tissue and cancers show up as white. That means a cancer can easily hide in a background of dense breast tissue.

Additionally, women with dense breast tissue have a higher risk of developing breast cancer than women with less fibroglandular tissue in their breasts.

Mammography is the only way to determine breast density. On the report, radiologists score density in four different categories:

• A (Fatty): Mostly fatty tissue
• B (Scattered Fibroglandular): Some scattered dense areas
• C (Heterogeneously Dense): Many dense areas; harder to spot small issues
• D (Extremely Dense): Very dense tissue; hardest to read

For women with dense breast tissue (categories C and D), supplemental screening with automated breast ultrasound (ABUS) is recommended in alongside your annual mammogram.

Callbacks

Being called back after a mammogram usually means the doctor needs a clearer or focused picture of a specific area. About one in 10 patients needs a callback, with vast majority turning out to be free of abnormal findings.

Common reasons for a callback after a screening mammogram include:

• Overlapping or dense tissue
• First (Baseline) mammogram
• Asymmetry: One side looks different from the other or from the surrounding tissue
• Calcifications: Tiny calcium spots within breast tissue
• Mass or lump
• Blurry or unclear pictures

Breast cancer symptoms

In addition to following the breast cancer screening guidelines, women need to know what is normal for their bodies. Breast cancers can develop in women who haven’t reached the age for routine screening or between screening mammograms.

The most common symptom of breast cancer is a new lump. A painless, hard, fixed mass that has irregular edges is more likely to be cancer, but breast cancer can also be soft, round, tender or painful. 

If you have these symptoms or other changes in your breasts or nearby lymph nodes, you should talk to your gynecologist or primary care provider about having them evaluated promptly.