Abnormal Screening Mammogram with Normal CBE ~ Algorithm 3
Breast Cancer Diagnostic Algorithms for Primary Care Providers
(Third Edition, June 2005)
With
improved imaging techniques, screening mammograms
are enabling detection of earlier breast cancers.
If an abnormality is suspected with screening
mammography, the radiologist performs additional
mammographic views and/or ultrasound. After
the imaging work-up is complete, the radiologist
assigns a BI-RADS® category 1-6 as the
final imaging result.
Introduction to the work-up of an Abnormal Screening Mammogram with
Normal CBE ~ Algorithm 3
With improved imaging techniques, screening mammograms are enabling detection of earlier
breast cancers. If an abnormality is suspected with screening mammography, the radiologist
performs additional mammographic views and/or ultrasound. After the imaging work-up is
complete, the radiologist assigns a BI-RADS® category 1-6 as the final
imaging result.
Final Imaging Results – Negative or Benign (BI-RADS® Categories 1 or 2)
Routine clinical follow-up is appropriate for Negative and Benign (BI-RADS® category 1 and 2) mammographic imaging results.
Final Imaging Result – Probably Benign (BI-RADS® Category 3)
A Probably Benign, BI-RADS® category 3 lesion generally will require a repeat CBE in 3-6 months and repeat mammography in six months to ensure concordance between the CBE findings and the radiographic lesion. If the woman is at increased risk for breast cancer, immediate follow-up is recommended with a breast specialist. Women with average risk may be referred for repeat CBE and imaging in six months (short-term follow-up). If the initial six-month short-term follow-up (unilateral mammogram) is stable, another bilateral mammogram in 6 months may be recommended by the radiologist (ACR, 2003 and Kerlikowske, 2003). If there is still no change, the patient should be rescreened at one-year intervals for two years. While a lesion’s radiographic stability over time suggests benignity, a lack of change in features cannot completely reassure the PCP and patient that a lesion is benign. There have been reports of microcalcifications, which are stable on radiologic exam, yet are later found to be malignant in 8-63 months (Michell, 2003). Some lesions classified mammographically as probably benign may be biopsied depending on the recommendations of the breast specialist and the preferences of the patient.
Final Imaging Results – Suspicious Abnormality or Highly Suggestive of Malignancy (BI-RADS® Categories 4 or 5)
All mammograms showing a Suspicious Abnormality or a lesion that is Highly Suggestive of Malignancy (BI-RADS® category 4 or 5) should result in biopsy.
Categories 3, 4, and 5 always require further evaluation despite the normal clinical breast exam. A reasonable percentage (50-90%) of category 4 and 5 lesions will be shown to be cancerous (ACR, 2003). In fact, it is the detection of these small or pre-invasive cancers by mammography that significantly contributes to the reduction in breast cancer mortality .
The false-negative rate for screening mammography is 8% to 10% (Shaw de Paredes, 2000). Breast density can compromise the ability of a mammogram to detect a mass, and lesions located near the sternum can be difficult to visualize (Mandelson, 2000). Over a 10 year period approximately 24% of women getting an annual mammogram will have at least one false positive mammogram.
Flowchart Notes and Footer
NOTE 3A: Screening mammogram results of Negative (BI-RADS® category 1) and Benign (BI-RADS® category 2) prompt routine rescreening for women with normal CBE exams.
NOTE 3B: Lesions identified with a screening mammogram require a diagnostic "work-up" (additional views and/or ultrasound) before a final imaging result can be assigned (ACR, 2003). Prior to assigning the final imaging result, a BI-RADS® category 0 may be temporarily assigned to indicate that additional views or tests are needed, or that previous mammographic results need to be reviewed.
NOTE 3C: The American College of Radiology does not recommend the assignment of a BI-RADS® 3 result to a screening mammogram. If you should receive a screening mammogram report with this result, refer the woman for additional diagnostic imaging. If a diagnostic evaluation has already been completed, continue work-up based on that diagnostic imaging result.
NOTE 3D: A patient with a final imaging result of BI-RADS® category 3 who is at increased risk for breast cancer (See Algorithm #1) should be immediately referred to a breast specialist. Referral to a breast specialist can be offered to women who are concerned about their results and do not want to wait six months for further follow-up.
NOTE 3E: For BI-RADS® category 3, the vast majority of findings will be managed with an initial short-term follow-up examination in 3-6 months, followed by additional examinations until stability is demonstrated (2 years or longer). There may be occasions when a biopsy is done (i.e. patient request or clinical concerns). Evidence from all the published studies indicates the need for biopsy if the lesion increases in size or undergoes morphologic change (ACR, 2003).
NOTE 3F: A BI-RADS® category 4 lesion should lead to biopsy, and a BI-RADS ® category 5 lesion requires biopsy (ACR, 2003). If the lesion is definitively diagnosed as benign after core biopsy and is consistent (concordant) with the radiological findings, excisional biopsy is not required (See Algorithm #7). The methods of biopsy include stereotactic or ultrasound-guided core biopsy for definitive diagnosis or needle localization followed by excisional biopsy with intraoperative confirmation of negative margins.
Footer:
*Diagnostic Imaging Evaluation will often include diagnostic mammogram and breast ultrasound, but can also include any radiographic imaging procedure recommended by the radiologist. A final BI-RADS category will be assigned to the case based on the results of all diagnostic imaging procedures. Women should return to routine screening once the diagnostic and/or treatment cycle is completed.
References
American College of Radiology (ACR). (2003). Appropriate imaging work-up of palpable breast masses. ACR Appropriateness Criteria. Retrieved Oct. 11, 2003, from http://www.acr.org/ac pda
American College of Radiology (ACR). (2003). BI-RADS® - Ultrasound . Reston, VA: Author
American College of Radiology. (2003). Breast imaging reporting and data system (BI-RADS) (4 th ed.). Reston, VA: Author
Kerlikowske, K., Smith-Bindman, R., Ljung, B., Grady, D. (2003). Evaluation of abnormal mammography results and palpable breast abnormalities. Annals of Internal Medicine , 139(4), 274-284.
Mandelson, M. T., Oestreicher, N., Porter, P. L., White, D., Finder, C. A., Taplin, S. H., et al. (2000). Breast density as a predictor of mammographic detection: comparison of interval-and screen-detected cancers. Journal of the National Cancer Institute, 92(13), 1081-1087.
Michell, M. J., & Miaad, A-A. (2003). Detection of subtle mammographic signs of malignancy. Applied Radiology, 32(9), 11-16.
Shaw de Paredes, E. (2000). Missed breast cancer: avoiding this pitfall. Applied Radiology, 29.
Updated: May, 2008. |
