What Does BI-RADS 2 Mean?

This page is for anyone whose mammogram report says BI-RADS 2. It explains what a benign result means, how it differs from 1 and 3, and what to ask.

BI-RADS is the Breast Imaging Reporting and Data System, a scale from 0 to 6 that converts what a radiologist saw into a single number.

Category 2 is benign. NCI's definition is that one word. The radiologist saw a finding, recognized it, and classified it as something that is not cancer.

It helps to compare this with category 1, because the numbers invite a misreading. Category 1 is negative — there was nothing to describe. Category 2 is benign — there was something, and the radiologist named it. Both carry the same risk figure in NCI's table: about 1 percent chance of a breast cancer diagnosis within the following year. A 2 is not a step closer to cancer than a 1. It is a differently shaped normal result.

NCI lists each category with the risk of a breast cancer diagnosis within one year.

• 0 — Incomplete. More imaging or older films are needed.
• 1 — Negative. About 1 percent.
• 2 — Benign. About 1 percent.
• 3 — Probably benign. About 2 percent.
• 4 — Suspicious. 2 to 95 percent, split into subcategories 4a, 4b and 4c.
• 5 — Highly suggestive of malignancy. About 95 percent.
• 6 — Cancer already proven by biopsy.

NCI notes that most screening mammograms are interpreted as negative or benign — categories 1 and 2 — and that about 10 percent of women screened in the United States are asked to return for additional evaluation.

This is the distinction that matters most on a report, and it is easy to miss when the numbers sit one apart.

A category 2 finding has a recognizable benign appearance. The radiologist is not hedging. No follow-up beyond routine screening is triggered.

A category 3 finding is probably benign — NCI puts it at about 2 percent — and the radiologist wants to confirm stability with a shorter-interval follow-up scan rather than a biopsy. That is a watch-and-wait plan with a date attached.

So if your report says 2 and no follow-up was scheduled, that is consistent, not an oversight. If your report says 3, the follow-up is the point, and keeping the appointment is what makes the plan work.

NCI observes that additional testing is less likely when prior mammograms are available for comparison. A finding that has looked the same for years is far easier to call benign than the same finding seen for the first time.

This is the practical argument for keeping your screening at one facility, or for making sure prior images are sent ahead when you change facilities. It is also a reasonable question to ask about your own report: were older mammograms available, and has this finding been there before?

A benign finding on imaging speaks to that finding. It does not certify the rest of the breast tissue.

NCI reports that invasive breast cancer is present but undetected in 6 to 46 percent of exams across studies, and that false negatives are more likely in dense breasts. That range spans very different populations and study designs, so it is not a number to apply to yourself — but the principle holds. A reassuring mammogram lowers the odds; it does not eliminate them.

What this means in practice: a new lump, a skin or nipple change, or a persistent localized pain is worth reporting to your care team even after a category 2 result, rather than waiting for the next scheduled scan.

Your report may also say how dense your breast tissue is. That is separate from your BI-RADS number. Dense tissue can make a mammogram harder to read, and NCI notes that false negatives are more likely in dense breasts. NCI also says people with dense breasts may be offered breast MRI or ultrasound along with mammography, but it is not known whether this leads to better health outcomes. If your report says dense, ask your care team what makes sense for you.

Ask the imaging center when and how you will get your results. A category 2 result does not call for the fast follow-up that a suspicious result does. If you have not heard anything, call the center rather than assuming.

• What exactly was the finding, and what is it called?
• Was it present on prior mammograms, and has it changed?
• Does anything about this change my screening interval?
• Does my report describe my breast tissue as dense?
• What changes should make me call before my next scheduled scan?

See Mammograms, Imaging Tests, and Cancer Screening Overview.

• https://www.cancer.gov/types/breast/hp/breast-screening-pdq