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When it comes to waiting for mammogram results, tensions can run high. Then, when your mammogram report arrives, you may find it confusing or unclear. It may help to understand the terminology the radiologist uses for each report.

Since the 1980s, the American College of Radiology has used the Breast Imaging Reporting and Data System (BI-RADS) system. BI-RADS is a standard reporting system for radiologists to use when writing mammogram reports. This makes it easier for patients and doctors who are not radiologists to understand the findings.

Getting to Know BI-RADS

BI-RADS tells radiologists how to describe mammogram findings. This includes descriptions (and examples) for:

  • Breast composition (fatty, dense).
  • Masses (shape, type of margin).
  • Calcification (calcium deposits within the breast).
  • Asymmetries (overall difference from one breast to the other).
  • Associated features (skin thickening, nipple changes).
  • Location of the area of concern (described using distance from the nipple).

BI-RADS also suggests a template for radiologists to use when they report findings. Expect your mammogram report to cover these topics in order:

  • Breast density.
  • Imaging findings (categories 0–6).
  • Overall assessment.
  • Management suggestions.

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What Do My Mammogram Results Mean?

BI-RADS also specifies that the radiologist will assign your mammogram an overall category number between 0 and 6. This number sums up any concerns the radiologist has.

Category 0 is incomplete, 1 is negative, 2 is benign, and 3 is likely benign. Categories 4 and 5 are abnormal results that mean a breast biopsy is needed. Category 6 results are for patients with a known malignancy.

The BI-RADS number also indicates what next steps you need to take if any. That number also tells you when you should have your next mammogram.

Negative or Benign Mammogram Results

On the BI-RADS scale, one is the best possible result. In general, the lower the number, the less likely it is that you have breast cancer.

Category 0: Incomplete

This means your test was incomplete. Perhaps you moved while the technician took the X-ray. Or the mammogram images may be difficult to read for some other reason.

Radiologists also use this category when they want to compare your current mammogram with an earlier one.

Category 1: Negative

This means your mammogram is negative. The radiologist did not see signs of breast cancer. Even with this negative result, continue to get mammograms as your doctor recommends.

Category 2: Benign

This means your mammogram did not show signs of cancer but the radiologist did describe noncancerous findings. These benign findings could include calcifications, cysts, or lumps of normal breast cells.

Category 3: Probably benign

This means that there were 1 or more findings that are probably not cancerous. In other words, your mammogram results are probably normal, but there is a 2% chance of cancer.

The radiologist will ask you to return for another mammogram within 6 months to see if the area changes over time. Expect your doctor to want to see several mammograms spaced 6 months apart.

Abnormal Mammogram Results

Radiologists use categories 4 and 5 to describe situations in which breast cancer is likely or very likely.

Category 4: Suspicious abnormality

This means your mammogram includes findings that could be cancer. The results are not definite, so the radiologist will recommend a breast biopsy to know for sure.

Category 4 is further divided into these three groups:

  • 4A means that your chance of having breast cancer is more than 2% but less than 10%.
  • 4B means that your chance of cancer increases to more than 10% but is less than 50%.
  • 4C means that your chance of having breast cancer is more than 50% but less than 95%.

Category 5: Highly suspicious

This means that your mammogram indicates at least a 95% chance of breast cancer. The radiologist will strongly recommend a breast biopsy to confirm these results. The breast biopsy will also give your doctor important information to use in treatment planning.

Category 6: Known biopsy with proven malignancy

This means that you’ve already had a biopsy and received a breast cancer diagnosis. Your doctor may order a mammogram to see how well your cancer is responding to treatment.

Knowing more about BI-RADS may not make your wait for your mammogram results easier. But you will be better prepared to understand your mammogram report when it does arrive. If your report includes abnormal mammogram results, you’ll have a better sense of how serious they are.

And whatever your results are, your doctor and the breast imaging team will guide you and work with you throughout your breast health journey.


American Cancer Society. Understanding Your Mammogram Report. Link

Surviving Breast Cancer. Is BI-RADS 5 Always Cancer? Link

Stat Pearls. Breast Imaging Reporting and Data System. 2020. Link

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