What Does BI-RADS 1 Mean?

This page is for anyone whose mammogram report says BI-RADS 1. It explains what a negative result means, what it does not rule out, and what to ask.

BI-RADS is the Breast Imaging Reporting and Data System, a scale from 0 to 6 that turns what a radiologist saw into a single number so every reader of the report understands the same thing.

Category 1 is negative. NCI's definition is exactly that word. There is no mass, no suspicious calcification, no architectural distortion — nothing the radiologist felt was worth describing.

Category 2 is benign. NCI gives the same one-year risk for both categories, about 1 percent. Ask your care team when your next screening is due.

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

• 0 — Incomplete. More imaging or older films are needed before a number can be given.
• 1 — Negative. About 1 percent.
• 2 — Benign. About 1 percent.
• 3 — Probably benign. About 2 percent.
• 4 — Suspicious. 2 to 95 percent (4a: 2-10 percent; 4b: 10-50 percent; 4c: 50-95 percent).
• 5 — Highly suggestive of malignancy. About 95 percent.
• 6 — Cancer already proven by biopsy.

NCI notes that about 10 percent of women screened in the United States are asked to return for additional evaluation, which means roughly 90 percent are not.

That 1 percent figure covers the year after the exam. It covers the year after the exam, which is one reason screening is repeated.

NCI also reports that invasive breast cancer is present but undetected in 6 to 46 percent of exams, depending on the population and the study, and that false negatives are more likely in dense breasts. That range is wide and reflects very different study designs, so it is not a number to apply to yourself. What it establishes is the principle: a normal mammogram lowers the odds substantially; it does not zero them.

What this means in practice: if you notice a new lump, a change in the skin or nipple, or a persistent localized pain after a normal mammogram, that is worth reporting even though your last scan was clean. A normal screening result is not a reason to wait for the next scheduled one.

Your report also carries a breast density statement, and it is independent of the BI-RADS category. Dense tissue does not raise your number. It changes how well the mammogram could see in the first place.

If your report mentions dense tissue, ask your care team whether that changes what screening is right for you. NCI says false negatives happen more often in dense breasts.

If you have not received your results, call the facility that did your mammogram and ask. Do not assume that no news is good news.

One practical note: NCI observes that additional testing is less likely when prior mammograms are available for comparison. Keeping your screening at the same facility, or making sure prior images are sent ahead, reduces the chance of a callback that turns out to be nothing.

• When is my next mammogram due, and who schedules it?
• Does my report describe my breast tissue as dense?
• Were prior mammograms available to compare against this one?
• Given my personal and family history, is annual screening the right interval for me?
• 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