It’s been two weeks since you had your mammogram and your “letter” arrives in the mail. You know that if they found something serious you probably would have been called by now to come back in but it still is nerve racking to open the letter.
This blog is intended to be your “buddy” to help you understand what your letter says. But more important, it shows you how to look behind the curtain and get ALL the information your doctors have about your mammogram, your risk of having cancer now, and your risk of getting cancer in the future.
Your letter will tell you two things: some language about what they found on the exam and some language about your overall breast density. These are very different results and you should focus on them separately. The first result is essentially “do you have cancer now?” The second result is “what is your future chance of cancer?”
With this overview let’s get into the weeds…
Following the rapid increase in mammograms in the 1980s, it became clear that a need existed for a standardized reporting format for the reports. A doctor in Nebraska needed to be able to talk to a radiologist in New Jersey about a mammogram from a few years ago in a common language. The community of radiologists developed the Breast imaging-reporting and data system (BI-RADS) for that purpose. The BI-RADS score on your mammogram provides a wealth of information; information you deserve to know.
At the same time, Congress passed a law that required that women who had a mammogram receive a “letter” within 30 days of the test, explaining the results. The good news is that almost all women are now getting this letter as required. The bad news is it doesn’t have all the information you deserve to know.
Over the years there have been a number of modified versions of the BI-RADS system adopted. But the overall format is a scoring system from 0 to 6 which correspond to increasing likelihood of a cancer being present. The categorization provides an approximate risk of cancer to a lesion from essentially zero to greater than 95%. This table is a “simplified” version of the scoring system that you can use.
| Score | Meaning | Likelihood of Cancer | What You Should Do |
|---|---|---|---|
| 0 | Incomplete evaluation with further imaging required including additional mammographic views including spot compression or magnification and or ultrasound | Not Applicable | Be sure they do more studies; either more mammograms or ultrasound or MRI |
| 1 | A negative examination. meaning that there are no masses, suspicious calcifications or areas of architectural distortion. There can be no description of a finding in the report if it is categorized as a BI-RADS 1. | Essentially 0% | Great news! Unless you have a change in your monthly self breast exam or other change, return for your next scheduled mammogram |
| 2 | Benign findings. Benign findings include secretory calcifications, simple cysts, fat-containing lesions, calcified fibroadenomas, implants and intramammary lymph nodes. | Essentially 0% | Routine screening interval |
| 3 | Probably benign. Should have shortened interval follow-up to determine stability. | <2% | Requires a diagnostic mammogram |
| 4 | Suspicious abnormality. which can represent the chance of being malignant (in percent). The BI-RADS category 4 is subdivided into a, b, and c. The subcategory of (a) has a low probability of malignancy with a 2% to 10% chance of malignancy. The subcategory of (b) has an intermediate change of malignancy ranging from 10% to 50%. The subcategory of (c) has a high probability of malignancy ranging from 50% to 95%. | 2 to 10%; 10 to 50%; 50 to 95% | Requires a diagnostic mammogram and perhaps a biopsy |
| 5 | Highly suggestive of cancer. | >95% | Requires a diagnostic mammogram and a biopsy |
| 6 | Known cancer. | 100% | Requires a diagnostic mammogram |
In addition to the above classification system, the last component of a mammography report under the BI-RADS classification system is management recommendations. There are only four options for management under the BI-RADS system. These recommendation options are: (1) additional imaging studies, (2) routine interval mammography, (3) short-term follow-up, and (4) biopsy.
The majority of mammograms are BI-RADS 1 or 2 and require only routine interval mammograms. About 7% will be BI-RADS 3 and only 2% will be BI-RADS 4 or 5 and require a biopsy.
In Summary: With respect to your current mammogram, you need to ask your doctor:
Until a few years ago, the above information was all that was reported by mammography. But after decades of exams and lots of research, a new finding emerged. It turned out that the “background” density of the breast, even in women with no current cancer lesions, was predictive of future breast cancer. This was a way to say: “based on all we know about you, your family history, and your breast density, you are at [low, medium, or high] risk of future breast cancer.
This year Congress has written a law that women need to be told in their mammogram letter about their density. So after the first paragraph about your current exam the letter will tell you if you have dense breasts or not. Most of the letters will just say you do or do not have dense breasts. And don’t panic if it says you have dense breasts; about 50% of all women have some level of increased density.
So what should you do with your information? Get the added information that your doctor gets about your density! Just like with the above system of BI-RADS scores for cancer suspicion there is a BI-RADS score system for density. Here it is:
| Score | What it means | Percent of Women | Sensitivity to finding Cancer | Risk of future breast cancer |
|---|---|---|---|---|
| A | Almost entirely fat; <25% | 10 | 88 | 1.0 |
| B | Scattered densities; 25-50% | 43 | 82 | <2.0-fold higher |
| C | Heterogenously dense; 50-75% | 39 | 69 | About 2.1-fold higher |
| D | Extremely dense; 75-100% | 8 | 62 | About 4.6-fold higher |
As you can see, there is differences in both how sensitive the mammogram is with different densities and the risk of increased breast cancer with density. Sensitivity is expressed as a percentage and means, if you tested 100 women with “known” breast cancer, how many cancers would you find? So 88% sensitivity means you would find 88 cancers and miss 12 cancer in that hypothetical example. With respect to risk of future cancer, the lowest risk is in the lowest density risk group and it goes up from there. These risk levels are similar to having a sister or mother with breast cancer.
In summary: With respect to density, you need to ask your doctor simply: “What is my density, A, B, C, or D?”
