Additional BIRADS 4 and 5 categories: Diagnostic workup.
Radiologists use a BI RADS classification system to categorise breast screening results. The BI RADS stands for Breast Imaging Reporting and Data System and was developed by the American College of Radiology
Each BI RADS category reflects an increased suspicion in the interpretation of the radiologist for the likelihood of being diagnosed with breast cancer. So, there are seven different mammograms, ultrasound and MRI BI RADS assessment categories. However, there are really only four possible outcomes.
- There could be additional imaging studies right away (ultrasound, MRI, or more detailed breast mammogram with extra views).
- Next, there could be a recommendation for ‘routine’ interval mammography. This means more regular follow-up mammograms and assessment.
- Or, the radiologists recommend a patient for a ‘short interval’ follow-up mammogram, this is usually in about 6 months time
- Finally, if the mammogram is worrying the radiologist may request an immediate biopsy.
Chance of breast cancer in BIRADS 4 reports
The range of findings associated with BIRADS 4 category breast lesions can be highly variable. Indeed, there are three subclasses (A, B, and C) of BIRADS 4 in light of this variability.
So, the positive predictive value of BIRADS 4 breast abnormalities on a mammogram is between 23% and 34%. This is not all that high at all.
With experience, a radiologist learns to fine-tune their own diagnostic techniques. So, as a result, radiologists send fewer patients for breast biopsy. Hopefully, only patients who are the most suspicious for breast cancer will have a biopsy.
Category 5 breast lesions, however, are very likely to be breast cancer with a positive predictive value ranging between about 80% and 97%.
BIRADS 4: Overall, after biopsy, the rate of breast cancer diagnosis is about 30%
Among initial findings on mammograms that require a biopsy, the most common category is a BIRADS 4 breast lesion. These lesions are ‘suspicious for malignancy’ and occur about 70% of the time.
BI-RADS category 5 lesions (highly suspicious of malignancy) account for about 13% of screening mammograms requiring biopsy. Breast lesions that are BI RADS category 3 on a mammogram. account for about 11% of biopsy requests.
BIRADS 4: The average time between screening and confirmed diagnosis is usually 2 to 7 days
Depending upon the radiologist’s interpretation of the mammogram, there may be more or less ‘urgency’ in finding out a definitive diagnosis.
On average, for women with a BI RADS category of 3 or 4 on a mammogram, the time interval between initial breast cancer screening and a definitive diagnosis is about 2 days.
However, for women with a BI RADS category of 4 or 5, additional imaging and biopsy studies may be necessary. So the average time interval before a diagnosis is, or ought to be about 7 days.
BI RADS assessments allow a radiologist to monitor their own diagnostic accuracy
BI-RADS category 3 lesions should not be biopsied
For a Category 3 BI RADS on a mammogram, specialists will usually not advise a breast biopsy. Nonetheless, a great number of BI-RADS 3 cases do end up having a biopsy. In many instances, the reasons for proceeding with a biopsy are not medically necessary but are related to patient anxiety or perhaps physician insecurity.
Also, women with ‘high-risk factors’ such as a family history of breast cancer, might also be biopsied with BI RADS category 3 mammograms. BI RADS category 3 lesions sent for biopsy have a negative predictive value (NPV) of between 97% and 100%. What does that mean? Well, it means that it is almost 100% certain that the abnormality is not breast cancer.
Among some breast cancer physicians, the use of Magnetic Resonance Imaging (MRI) may be encouraged for BI-RADS category 3 lesions as a means of immediate follow-up, rather than biopsy. A breast lesion with a BI RADS category 3 is really highly predictive of benignity. So, the radiologist may request follow-up imaging or encourage short-term (6 months) follow-up as an alternative to biopsy.
The Positive predictive value typically increases for palpable breast masses
If a breast lesion on a mammogram is also clinically palpable on physical examination the medical practitioner will want to know if the tumor has liquid or solid elements.
However, the features of a solid mass on a mammogram are an irregular shape with spiculated margins.
Also, if the mass shows microcalcifications with a segmental distribution and a linear morphology the radiologist will be increasingly suspicious of malignancy.
These are just some of the mammographic indicators which come into play with a BI-RADS 4 category assessment and the decision whether or not a biopsy is necessary. The positive predictive value of breast cancer in BI RADS category 3 and 5 lesions remains about the same.
This is regardless of whether the lesion is palpable or not. But in suspicious breast masses, categorized as BI-RADS 4, the positive predictive value increases by up to 30% if the lesion is physically palpable.
Vacuum-assisted device (VAD) used for adequate sampling.
The different means and types of biopsies for breast cancer staging purposes can be a bit confusing. In general, your doctors will try to minimize the amount of ‘invasiveness’ or surgery required in order to get biopsy samples unless it is absolutely necessary.
An important goal of a biopsy in a BI-RADS Category 4 lesion is to gain an adequate sample size and to make sure there is an accurate assessment of the extent of the carcinoma.
Often a vacuum-assisted device (or VAD) biopsy will be utilized, as it is a useful tool to examine microcalcifications and breast masses less than 1.5 cm in diameter without causing too much discomfort for the patient. Typically, a surgeon will take up to 20 samples using an ’11 gauge’ probe.
Concern for ‘displacement’ with BI RADS category 5 lesions.
Some experts express concern about biopsies for category 5 lesions, feeling that the epithelial displacement of tumor cells might accelerate growth. Once removed from the body cancer cells degenerate and die.
However, surgeons prefer that the mass site is disturbed as little as possible. So, a surgeon will obtain a minimal amount of large biopsy using core needle biopsy.
The surgeon will then wish to establish the histologic grade of the tumor, evaluate the sentinel node (the first few lymph nodes around the tumor) , and sample hormonal levels. Some physicians prefer the use of a ‘Fine Needle Aspiration’ (FNA) biopsy rather than large core samples when the lesion is solid and with high cellular content. But, an FNA biopsy is insufficient to distinguish between DCIS and infiltrating ductal carcinoma (infiltrating ductal carcinoma being a more advanced stage.)
The main goal of any biopsy with BI-RADS category 5 is to confirm the diagnosis and extent of an obviously malignant lesion. Additional diagnostic procedures, particularly imaging and possibly biopsy of the axillary lymph nodes, will almost always be necessary. Many surgeons will remove the breast lesion in a one-step therapeutic surgery and will thus seek to disturb the site, and the patient, as little as possible.
“Short interval follow-up” is usually sufficient
Certainly, breast cancer screening mammography has the goal of detecting breast cancer at the earliest possible stage and ultimately to prevent breast cancer mortality.
However, another important aspect of breast cancer screening, in general, is to minimize the harm, both physical and psychological, associated with screening women who are healthy and do not have breast cancer.
Given a large sample of an average population, one can expect a certain amount of ‘initially positive’ readings, requiring short-interval follow-up.
Approximately 5% of screening mammograms require follow-up or ‘diagnostic’ investigation, though the decision to follow-up is somewhat subjective and that number can vary from center to center.
The follow-up rate can vary between almost 10% and as low as 1%. But the actual rate of breast cancer diagnosis for women requiring short interval follow-up requiring either additional imaging studies of biopsy is only about 1%.
Common Questions and Answers
My screening report shows that I have breast microcalcifications. Does this mean I have cancer?
Breast calcifications are very common, especially as women age, and are usually harmless (benign microcalcifications). These calcifications are tiny deposits of calcium present in breast tissue.
I have a report that states ‘biopsy recommended’ what does this entail?
There are several types of biopsy useful for diagnostic purposes. Surgical biopsy (or open biopsy) is quite rare for diagnostic purposes. Surgeons perform the most common types of biopsy under a local anesthetic and these are painless. So, types of biopsy include fine-needle aspiration and core-needle biopsy.
I have received my mammogram report and it states that my breasts are heterogeneously dense. What does this mean?
Most mammogram reports will include a description of breast density. How dense the breasts are relates to the proportion of fibrous and glandular tissue in relation to fatty tissue.
If the report states that there are ‘scattered fibroglandular densities’ this means that the breasts are mainly fatty with small areas of fibrous and glandular tissue. If there is a high breast density it lowers the accuracy of the mammogram and has been associated with an increased risk of cancer.
- Mazouni C, Sneige N, Rouzier R, Ballyguier C, Bevers T. (2010) A nomogram to predict for malignant diagnosis of BI-RADS category 4 breast lesions. Journal of Surgical Oncology (Sept. 2010) Volume 102, Issue 3, pages 220–224. https://www.ncbi.nlm.nih.gov/pubmed/20740578
- Taplin S, Ichikawa L, Kerlikowske K, Ernster V, Rosenberg R, Yankaskas B, et al. (2002) Concordance of Breast Imaging Reporting and Data System assessments and management recommendations in screening mammography. Radiology (2002);222:529–35. https://www.ncbi.nlm.nih.gov/pubmed/11818624
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