Is BI-RADS 5 Always Cancer?

By Kimberly Stephenson

After a mammogram, the answers to questions like “Did anything look abnormal?” and “How serious is the abnormality that was found?” help radiologists and physicians to determine your BI-RADS score. Your BI-RADS score is an acronym for ‘Breast Imaging Reporting and Database System’. The score ranks the findings from mammogram screenings into a small number of well-defined categories.

BI-RADS scores are used to convey to doctors how concerned radiologists are about the findings. The information obtained by the radiologist is efficiently summed up in that one number. While this test cannot medically diagnose breast cancer, it can help to identify anything atypical. However, it is important to note that not all abnormal findings are considered cancerous.

What Does the BI-RADS Scoring System Tell Us?

Doctors use the BI-RADS scheme to place abnormal findings into categories. The categories range from 0 to 6, and are as follows:

Category 0:

A score of 0 indicates an incomplete test. The mammogram images may have been difficult to read or interpret. This could happen, for example, if you moved at the precise moment the picture was taken. In some cases, doctors may want to compare these new images with older ones to determine if there have been any changes. A BI-RADS score of 0 requires additional tests and images to provide a final assessment.

Category 1:

A score of 1 indicates a negative result. This score is good news. It means that your mammogram has no evident signs of cancer, your breast has equal density, and no well-formed mass was found. However, you should continue to have routine screenings even after a BI-RADS score of 1.

Category 2:

A score of 2 indicates a negative result but with benign findings. Your mammogram is normal, with no apparent cancer, but other findings (such as benign cysts or masses) are described in the report. Routine visits are suggested with this score.

Category 3:

A score of 3 indicates that findings are probably benign. This score is not so black and white, as the findings imply that your mammogram results are probably normal, but there is a 2% chance of cancer. You will be asked to follow up with a repeat mammogram within six months. If you have a family or personal history of breast cancer, the radiologist may opt to do more tests sooner rather than later. Regular visits help avoid multiple and unnecessary biopsies and can confirm an early diagnosis if cancer is found.

Category 4:

A score of 4 indicates suspicious findings or abnormalities. This level is where concern for breast cancer risk begins to increase. In this instance, there is a 20% to 35% chance of cancer. To verify, your doctor will need to perform a biopsy to test a small tissue sample. This score is split into three additional categories based on the doctor’s level of suspicion:

1. 4A - Low suspicion for cancer or malignant findings (more than 2% but no more than 10%)

2. 4B - Moderate suspicion for cancer or malignant findings (more than 10% but no more than 50%)

3. 4C - High suspicion for cancerous or malignant findings (more than 50% but less than 95%)

Category 5:

A score of 5 indicates highly suspicious findings. In this instance, there is at least a 95% chance of breast cancer. A biopsy is highly recommended to confirm results and determine the next steps for treatment. After biopsy, the average rate of carcinoma in category 5 is about 75-97%.

Category 6:

A score of 6 indicates a known biopsy with proven malignancy. You can only score a 6 after you’ve had a biopsy and received a diagnosis for breast cancer. Mammograms may be used in this way to see how well the cancer is responding to treatments such as chemotherapy, surgery, and/or radiation.

How Do BI-RADS and Breast Density Relate?

Two main types of tissue make up the breast: fibroglandular tissue and fatty tissue. On mammograms, Fibroglandular tissue appears dense, whereas fatty tissue does not. Most women have both dense and non-dense (fatty) tissues. The volume of dense tissue compared to the amount of non-dense tissue in your breast is commonly described as your breast density.

Dense breasts have less fatty tissue, meaning they are more likely to develop cancer in comparison with less dense breasts with more fatty tissue. The volume of dense tissue in your breast can be measured by radiologists by using BI-RADS.

It is important to note that although breast density can be seen on a mammogram, it is not related to the actual size or even the feel of your breasts. Breast density varies from person to person and can even change over time as we get older.

BI-RADS also classifies breast density into 4 categories. They are as follows:

• Mostly fatty - Breasts are composed almost entirely of non-dense (fatty) tissue

• Scattered Density - Breasts are composed mainly of non-dense (fatty) tissue, with some scattered areas of dense tissue.

• Consistent Density - Breasts are composed of a mixture of non-dense (fatty) tissue and dense tissue.

• Extremely Dense - Breasts are composed of almost entirely dense tissue

Breast density is important because the denser the breast, the harder it is to detect abnormalities. Normal dense breast tissue looks white on mammograms. Breast masses or tumors also look white, so dense tissue can hide some tumors. However, this does not mean that you should be alarmed if you have dense breast tissue. It simply means that you should speak with your health care provider about your overall breast cancer risk. Regardless of the density of your breast, it is important to keep up with your mammograms!

Does a BI-RADS Score of 5 Always Equate to Cancer?

Although this is a seemingly straightforward question, the answer is not. The use of BI-RADS can aid in standardized reporting, steering decision-making, and operating as a useful tool in collecting medical data. Each BI-RADS ranking reflects an increased suspicion of breast cancer diagnosis. When a patient is given any BI-RADS score, a cancer diagnosis cannot be wholly confirmed. The score simply assists doctors in communicating your mammogram results while determining the right course of treatment.

The main goal of any biopsy with BI-RADS category 5 is to validate the diagnosis and scope of an obviously malignant lesion. Additional diagnostic procedures, particularly imaging and possibly biopsy of the axillary lymph nodes, will almost always be necessary. Although a BI-RADS score of 5 highly suggests malignancy, it does not necessarily provide a complete cancer diagnosis. The only solidified fact is that appropriate action should be taken for the health and well-being of the patient.

Whether your BI RADS score is 0 or 5, knowing and understanding your score will help ensure that you get the appropriate follow-up after your mammogram. It is part of what you need to know to actively take part in and make informed decisions regarding your medical care.

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Check out our Podcast with Dr. Paula Gordon, a Radiologist from Vancouver on mammography and screening!

To read a personal story from one of our thrivers regarding mammographs and breast density, check out Leslie’s Story!