**5. Conclusions**

Our results provide support for inclusion of BTD into IBISv8 tool for purposes of HROBSP assessment of unaffected women, aged 40–69 y as it impacted the eligibility for MRI in 17% of women. The overall number of patients eligible for B-MRI was not significantly different when density was included, implying that there would not be a substantial impact to the resource requirements of the HR-OBSP. Family physicians are instrumental in assessing patient's risk for BC. If aware of a family history of BC in a woman 40 years or older, family physicians should order a mammogram to obtain BTD, as incorporating BTD will help to refine and improve risk assessment.

**Author Contributions:** Conceptualization, J.M.S., E.T., E.C., S.P. and A.R.; methodology, A.R., J.M.S., S.P., E.A. and E.T.; software, S.R., R.F. and K.R.; validation, E.A., V.H., E.S., K.A., S.Z., S.M., and C.A.; formal analysis, N.I., J.M.S. and R.F.; investigation, S.R., K.R., V.H., E.S., K.A., S.Z., C.A., S.M., S.P., J.M.S., E.T. and A.R.; resources, E.A. and J.M.S.; data curation, R.F. and J.M.S.; writing—original draft preparation, J.M.S.; writing—review and editing, A.R., E.T., S.P., E.C., V.H., E.S., K.A., S.Z., S.M., and C.A.; visualization, J.M.S. and A.R.; supervision, E.A., E.T. and A.R.; project administration, E.A.; funding acquisition, E.A. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Institutional Review Board Statement:** Ethical review and approval were waived for this study due to Ottawa Hospital Research Institute approved as QI project.

**Informed Consent Statement:** Patient consent was waived due to approved QI project.

**Data Availability Statement:** Data Availability upon request in Dataverse.

**Conflicts of Interest:** The authors declare no conflict of interest.
