Breast cancer screening in Canada: 2021/2022

Breast density

Evidence has shown that having dense breasts is associated with an increased risk of developing breast cancer, and that having dense breasts can make it more difficult to detect breast cancer by mammogram alone. What is not clear, however, is whether more frequent mammographic screening or “supplemental screening” with ultrasound or MRI improves outcomes for these people.

In Canada, some jurisdictions classify individuals with high breast density (defined as ≥ 75% glandular tissue) as being at elevated risk; usually these individuals are eligible for more frequent screening.

Ten provincial and territorial breast screening programs collect information on breast density. Nine jurisdictions notify participants of their breast density assessment alongside their mammography results and a breast density fact sheet. Others do not directly notify the participant of their breast density assessment; however, they inform the participants’ primary care provider.

Digital tools and technology used to assist in breast density assessments

AB: Some sites are using artificial intelligence tools to assist with density reporting – these sites will override AI if radiologists disagree with the tool.

NB: The RHAs are currently pilot testing AI software.

NS: Nova Scotia Breast Screening Program uses an automated algorithm (densityaiTM by Densitas®)

PE: The program is using a software program (Densitas®) to complement radiologist density software

Definition and data collection for high breast density by screening programs

P/T Definition of high breast density Does the program collect information on breast density? Does the program recommend more frequent screening for those with high breast density?
YT BI-RADS* category D
NT ≥ 75% glandular tissue
AB ≥ 75% glandular tissue
SK ≥ 75% glandular tissue
MB BI-RADS* category D
ON ≥ 75% fibroglandular tissue
(recalled in 1 year instead of 2 years)
QC ≥ 75% glandular tissue
NB BI-RADS* classification C (heterogeneously dense) or D (extremely dense)
(the Program’s legacy database is currently unable to collect this new BIRADS classification data set;  Historical data of categories as < or > 50%; data is what is available)
Recommendations for the management of High Breast Density are under development as part of Increased/High Risk CPGs; Currently supplemental screening is based on Radiologist recommendations
NS Category C (heterogeneously dense) or Category D: (extremely dense) Radiologist can recommend more frequent breast screening.
PE ≥ 75% glandular tissue
NL ≥ 75% glandular tissue

YK, BC, MB, NB: * Breast Imaging and Reporting Data System (BI-RADS) categories for breast density: A- almost entirely fatty (<25% glandular); B- scattered fibroglandular densities (25-50% glandular); C- heterogeneously dense (51-75% glandular); D- extremely dense (>75% glandular).
BC: ^ BC radiologists categorize breast composition using BI-RADS to assess the volume of breast density. The C and D categories are commonly referred to as “dense”. BC Breast Screening currently provides BI-RADS assessment for participants and providers; however, it has no definition for “high breast density”.

Notification of participant’s breast density

P/T Are participants notified of their breast density? If participants are not notified of their breast density, are there any plans to send out notifications?
Participants can request information from their PCP; all screening reports include density information.
Not at this time – working on a plan to implement this
Documented on mammogram report to PCP but not included on results letter received by participants.
Intend to explore
BC Yes
They receive their BI-RADS breast density assessment with their results and an informational brochure.
AB Yes
Participants receive their BI-RADS breast density assessment with their results; additional information may be provided in pamphlet or accessed online.
SK Yes*
Approximately one week after their mammogram they receive a letter informing them that they have breast density along with a recommendation to screen annually and an information leaflet about breast density.
Program is working on how to implement standardized reporting throughout screening and diagnostic settings.
MB Yes
They receive their BI-RADS breast density assessment with their results and an informational brochure.
ON Yes
Participants with≥ 75% fibroglandular tissue receive a screening result letter accompanied by a breast density fact sheet. The letter informs the participant that their next mammogram should be in one year due to dense breast tissue as seen on their mammogram.
In April 2020, the OBSP launched the Breast Density Notification project to ensure OBSP participants can access their Breast Imaging Reporting and Data System (BI-RADS) breast density classification, and develop evidence-informed educational materials and communications to support enhanced breast density notification.
The recently updated OBSP Screening Report form requires radiologists to report both a percentage mammographic density and BI-RADS breast density category. All OBSP participants’ PCPs receive both breast density measurements.
The two-year normal result letter has also recently been updated to inform participants that they can access their breast density information from their family doctor, nurse practitioner or the OBSP site where their mammogram was performed.
PCP receives report with breast density. PCP can inform the patient.
NB Yes
Participants are notified of their breast density (BI-RADS category) in their screening results letter, accompanied by a breast density info sheet.
NS Yes
Participants are notified of their breast density (BI-RADS category) in their screening results letter, accompanied by a breast density fact sheet.
PE Yes
As of Jan 2020, participants receive a screening result letter with their breast density indicated and a density fact sheet. Prior to this, the PCP was notified of breast density information.
NL Yes
Patient are told in results letter that MBD is greater than 75% or less than or equal to 75%.

SK: *Informed that they have dense breasts, but not informed what their dense percentage is