Additional BI-RADS category 4 and 5 diagnostic workup.
BIRADS is a classification system used by radiologists to categorise breast screening results. BIRADS 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. Although there are seven different BI-RADS mammogram (and breast ultrasound and mri now) assessment categories, 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, which means a patient will be re-evaluated at her next routine scheduled annual mammogram.
- Or, a patient could be recommended for a ‘short interval’ follow-up mammogram, which is usually in about 6 months time,
- or finally, an immediate biopsy could be recommended.
Chance of breast cancer in BI-RADS 4 reports
The range of findings associated with BI-RADS category 4 breast lesions can be highly variable. Indeed, there are three subclasses (A, B, and C) of BI-RADS 4 in light of this variability.
But on the whole, the positive predictive value of category 4 mammographically detected breast abnormalities is between 23% and 34%, which is not all that high at all.
With experience a radiologist learns to fine tune their own diagnostic techniques and send less patients for biopsy or only those which are the most suspicious for breast cancer.
Category 5 breast lesions, however, are very likely to be breast cancer with a positive predictive value ranging between about 80% and 97%.
Overall, when biopsy is requested, the rate of breast cancer diagnosis is about 30%
Among initial findings on mammograms that require biopsy, the most common BI-RADS category is a category 4 breast lesion (which 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 identified at mammograph screening and classified as BI-RADS category 3 or ‘probably benign’ account for about 11% of biopsy requests.
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 in which the mammogram was assessed as a BI-RADS category of 3 or 4, the time interval between initial breast cancer screening and a definitive diagnosis is about 2 days. However, if a women is assessed at BI-RADS category 4 or 5, additional imaging and biopsy studies are usually required, and the average time interval before 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
Breast lesions detected on mammogram at BI-RADS category 3 are really not advised to go for biopsy evaluation. Nonetheless, a great number of BI-RADS 3 cases are sent for biopsy. In many instances the reasons for proceeding with a biopsy are not medically derived, but are related to patient anxiety or perhaps physician insecurity.
Also, women with ‘high risk factors‘ such as family history of breast cancer, might also be biopsied with BI-RADS category 3 mammograms. BI-RADS category 3 lesions sent for biopsy on average have a negative predictive value (NPV) of between 97% and 100%, which means 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 placed into a BI-RADS category 3 is really highly predictive of benignity, so either more detailed follow-up imaging or short-term (6 month) follow-up should be encouraged as an alternative to biopsy.
The Positive predictive value typically increases for palpable breast masses
If a breast lesion undergoing mammogram screening is also clinically palpable on physical examination then the medical practitioner will likely want to find out if it is composed of liquid or solid elements. In other words, they will want to differentiate between a breast cyst, or a solid mass. This is usually done via an ultrasound, but fine needle biopsy with aspiration can also accomplish this task. If it is a solid mass, then the mammographic features which generally have the highest positive predictive value for breast cancer would be an irregular shaped mass and spiculated margins.
Also, the radiologist would have an increased suspicious of malignancy if the mass showed microcalcifications with a segmental distribution and a linear morphology. These are just some of the mammographic indicators which come into play with a BI-RADS category 4 assessment and the decision whether or not a biopsy is required. The positive predictive value of breast cancer in BI-RADS category 3 and category 5 lesions remains about the same 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, if deemed necessary, is to gain an adequate sample size and to make sure the extent of the carcinoma is not underestimated. Often a vacuum-assisted device (or VAD) biopsy will be utilized, as it is a 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 up to 20 samples are taken using an ’11 gauge’ probe.
Concern for ‘displacement’ with 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, it is thought best that the mass site is disturbed as little as possible. A minimal amount of large biopsy samples are typically obtained using core needle biopsy. The surgeon will 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 a presumed high cellular content. But, a 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 undertaken. 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.s The follow-up rate can very 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
- I have been told from my screening report that I have breast microcalcifications. Does this mean I have cancer? Breast calcifications are very common, especially as a woman ages and are usually harmless (benign microcalcifications). These calcifications are tiny deposits of calcium found in breast tissue.
- I have a report that states ‘biopsy recommended’ what does this entail? There are several types of biopsy used for diagnostic purposes. Surgical biopsy (or open biopsy) is quite rare for diagnostic purposes. The most common types of biopsy are performed under a local anesthetic and are painless. These 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.
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