What Does BI-RADS 6 Mean?

This page is for people who see BI-RADS 6 on a breast imaging report. It explains why this category exists, what it does and does not tell you, and what to ask.

BI-RADS is the Breast Imaging Reporting and Data System, a scale from 0 to 6 used on breast imaging reports.

Categories 1 through 5 all answer the same question: based on these images, how likely is it that this is cancer? Each of those categories is a judgment about likelihood.

Category 6 is different in kind. The federal mammography rule (21 CFR 900.12) calls it known biopsy-proven malignancy, for cancers being checked on imaging for treatment planning. There is no probability attached because there is nothing left to estimate. A pathologist looked at tissue and found cancer before this scan was taken.

If you are reading a 6 on a report after you have already been told you have breast cancer, it is not new information. It is the radiologist recording the context they were working in.

Imaging does not stop once a cancer is diagnosed. Scans are used to look at how extensive the disease is, to check the other breast, to plan surgery, and in some situations to see how a tumor is responding to treatment given before surgery.

Those studies still have to be assigned an assessment category under the reporting rules. Without a category 6, a radiologist looking at a confirmed cancer would have to choose between calling it "suspicious" — which would imply a biopsy is needed when one has already been done — or leaving it unlabeled.

So a 6 tells every subsequent reader of the report a specific thing: the finding here is a known cancer, the biopsy question is settled, and the purpose of this study is something other than deciding whether to biopsy.

This is the most useful thing to take from the category, and it is a negative.

A BI-RADS 6 carries no information about the type of cancer, its grade, its hormone receptor or HER2 status, its size, whether lymph nodes are involved, or its stage. It does not indicate how advanced the cancer is, and it is not a measure of severity.

All of that lives elsewhere. The pathology report from your biopsy describes what the cells are. Stage comes from the size and extent of the tumor plus what the workup shows about spread. Treatment planning draws on both.

If you are trying to understand your situation, the BI-RADS number is not the document to read closely. The pathology report is.

The scale runs from 0 (incomplete) through 1 (negative), 2 (benign), 3 (probably benign), 4 (suspicious) and 5 (highly suggestive of malignancy) to 6. Categories 1 through 5 estimate likelihood. Category 6 records a cancer already proven by biopsy, so it is not a step up in severity from 5.

A confirmed cancer diagnosis is the point at which several decisions start moving quickly — surgery, systemic treatment, sequencing. It is also the point at which a second opinion is most often useful, because it is still early enough to change the plan.

That is a conversation for your care team, and there is no single right answer about whether to seek one. But asking what the plan is, what it depends on, and when the next decision point falls is reasonable at any stage.

• What is this particular imaging study looking for?
• What does my pathology report say — type, grade, receptor status?
• What is my stage, and is anything still needed to establish it?
• What are the treatment options being considered, and what is the sequence?
• Who is coordinating my care across specialists, and how do I reach them?
• Is a second opinion on the pathology or the treatment plan worth pursuing here?

See Pathology Reports, Cancer Staging, and Getting a Second Opinion.

• https://www.cancer.gov/types/breast/hp/breast-screening-pdq (opened; it does not list the category definitions)
• 21 CFR 900.12, read via https://www.law.cornell.edu/cfr/text/21/900.12 (eCFR was blocked)