Breast cancer screening in Canada: 2021/2022

Strategies to reach the abnormal call rate target

The abnormal call rate (ACR) – the percentage of mammograms identified as abnormal – is a key quality indicator of breast screening programs. In Canada, an increase in ACR without any corresponding increase in the cancer detection rate has been observed. Improving ACRs could minimize potential harms from over-screening and avoidable follow-up tests to ensure the benefits of screening are maintained.

Efforts have been made in Canada to support programs in optimizing their ACR. In 2020, the Partnership released the Pan-Canadian Framework for Action to Address Abnormal Call Rates in Breast Screening, which outlined a number of strategies to optimize ACR.

Eleven jurisdictions have used this Framework and other CPAC work to inform their strategies.

Strategies being implemented to reach the abnormal call rate target

P/T Min. reading volume Double reading Audit and performance feedback Comparisons with prior mammogram Number of mammo-graphic views Mammo-graphic compression Batch reading of mammogram Fellowship training in breast imaging
NT ✓4
BC ✓4
AB ✓ (varies by clinics) ✓ (intend to explore) ✓4 ✓ (intend to explore) ✓ (varies by clinics)
SK ✓ (tech supervisors – discrepancies are reviewer by a 2nd rad) ✓ (intend to improve) ✓ (some rads, not all)
MB ✓4 ✓ (some rads, not all)
ON ✓4 ✓ (encouraged at the site level) ✓ (some rads, not all)
QC ✓ 4
NB ✓4 ✓ (may vary by screening site)
NS ✓4 ✓*
(encouraged at the site level)
✓ (some rads, not all)

NS: *In Nova Scotia, some radiologists have fellowship training in breast imaging.

Read more about how provinces and territories are lowering abnormal call rates:

British Columbia icon

British Columbia
The program has modified its performance feedback stats to highlight areas of opportunity for improvement.

Alberta icon

The program provides regular performance reporting and works through clinic group leads to support low volume readers. Analysis on tomosynthesis use in Alberta and its impact on outcomes is ongoing.

Saskatchewan icon

The program provides quarterly statistics to radiologists of its ACR and volume of reads, as well as yearly reports of its positive predictive value, ACR, interval cancer rate and volumes in a de-identified comparison to other radiologists in the program. It is also working to standardize equipment throughout the province and implement the use of artificial intelligence in the screening program. On-site reading is also required.

Manitoba icon

In collaboration with the medical lead from BreastCheck, the program prepared a report to inform on program ACR, identify benchmarks and establish informed mentoring opportunities. On-site reading is mandatory (no remote access) and program stats are published and distributed monthly.

Ontario icon

The program encourages regional engagement for radiologists with low mammography volumes.

Quebec icon

The program coordinates a working group to find strategies to reduce ACR. Strategies discussed at the ACR working group, such as modifying performance feedback stats to highlight areas of opportunity for improvement, will be implemented once the pandemic is over.

New Brunswick icon

New Brunswick
Breast cancer screening rates decreased between April and August 2020 but have since returned to pre-COVID-19 levels. Breast screening invitation letters and awareness campaigns were put on hold between March and June 2020 and have since resumed. Screening sites have implemented various strategies, including double bookings and weekend clinics, to catch up on the backlog of mammography booking requests and to decrease wait times for bookings. Some screening sites are asking about COVID-19 vaccination pre-mammography for radiologists’ information.

Nova Scotia icon

Nova Scotia
The program has modified its performance feedback stats to highlight areas of opportunity for improvement. It has also established a working group on ACR. Strategies have been discussed at an ACR workshop and will be implemented once the pandemic is over.

Prince Edward Island icon

Prince Edward Island
The program continues to monitor ACR on a regular basis and follow ACR improvement methods such as performance feedback, batch reporting, comparison reads, minimum reporting volumes, standardized mammography views, compression practices, minimized distractions, etc.

The program plans to implement a quality assurance/improvement program control module (e.g., Densitas®) for educational purposes and to assist with positioning. There are also plans to purchase new equipment in late 2021 or early 2022, including tomosynthesis and CAD options, which will help address ACR and complement radiologist reporting.

Newfoundland and Labrador icon

Newfoundland and Labrador
The program has created a real-time dashboard for its screening program that enables the medical director to monitor program ACR and individual radiologists’ ACR for any period of time. The program’s current ACR for all screens is 5.7%. The medical director and program manager provide report cards to all radiologists on their performance relative to their peers.

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