Abnormal Interpretation Rate

This Mammologix Mini-Minute is about the abnormal interpretation rate in mammography, otherwise referred to as the recall rate.

Listen to this Mammologix Mini Minute

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When an examinee has a screening mammogram there are 3 interpretation reported outcomes possible.

The first includes an interpretation by the film reader that the mammogram shows no findings of breast cancer. Examinees with these findings are assessed as either a Bi-Rads Category 1 or 2.

The second is an interpretation of some finding significant enough to require follow-up that could include additional imaging - as indicated by an assessment of a Bi-Rads Category 0 or possibly Category 3. Additionally, on occasion a screening patient may  have a finding significant to be assessed as a Bi-Rads Category 4 or 5, requiring tissue sampling. 

Any of these 4 assessments are considered to be positive findings and are included in the determination of the abnormal interpretation rate in a screening breast imaging practice.

The third interpretation outcome is reserved for those isolate cases where an examinee undergoes screening mammography after having a prior breast cancer that was proven with tissue diagnosis. In this case, the Bi-Rads Category 6 and is not classified as either a negative or positive finding with regards to calculating recall rate.

According to the Breast Cancer Surveillance Consortium and the American College of Radiology's National Mammography Database, the benchmark for the abnormal interpretation rate is just over 10%. 

This means out of 100 screening mammograms performed, 90 examinees will be assessed as negative, while the remaining 10 will have an abnormal finding that requires additional follow-up.

According to the American Cancer Society, of the 10% of examinees who have a screening mammogram and are called back for more tests, 8% - 10% will need a biopsy, with 80% of those biopsies resulting in benign findings.  So, for every 1000 screening mammogram examinees, this averages out to be a detection rate of 2 to 4 cancers.

More specifically, the BCSC has identified 10.8% as the 50th percentile abnormal interpretation rate with 8.4% and 14.7% being the 25th and 75th percentile parameters for film readers interpreting at least 1000 screening mammograms or more during the period the data was collected.

To see how your film readers stack up against this benchmark use the mammography medical outcome audit produced by Mammologix. There you will find both the group practice abnormal interpretation rate, along with each individual film reader's individual recall rate.

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Souces
The information used to compile this segment was collected from sources including an article published December 5, 2016, online at Pubs.RSNA.org entitled; National Performance Benchmarks for Modern Screening Digital Mammography: Update from the Breast Cancer Surveillance Consortium, and references from a Breast Cancer Surveillance Consortiums report titled; Smoothed Plots of Frequency Distributions of Recall Rate for 1,642,690 Screening Mammography Examinations (Among Radiologists with 1000 or More Examinations), 2007 - 2013 Based on BCSC data through 2013.

• Pubs.rsna.org. (2019). [online] Available at: https://pubs.rsna.org/doi/10.1148/radiol.2016161174 [Accessed 20 Jan. 2019].
• NCI-funded Breast Cancer Surveillance Consortium (P01CA154292, U54CA163303, U01CA86076, U01CA63731, U01CA63740, U01CA70040, U01CA86082, U01CA70013). Downloaded 20 Jan. 2019 from the Breast Cancer Surveillance Consortium Web site - http://www.bcsc-research.org/