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Abstract
Purpose
Women with a remaining lifetime risk of breast cancer ≥25%, estimated using the International Breast Cancer Intervention Study (IBIS) model, are eligible for the High Risk Ontario Breast Screening Program (OBSP). This study examined the performance of IBIS 10-year risk estimates in the Program.
Methods
This retrospective study included 7487 women aged 30–69 years referred to the High Risk OBSP between July 1, 2011, and December 31, 2016, with follow-up until December 31, 2018. Model calibration and discrimination were assessed. Analyses were conducted overall and stratified by age (< or ≥50 years). Different 10-year risk thresholds were compared to the current eligibility criteria.
Results
Overall, IBIS over-estimated the risk of breast cancer with an E/O ratio of 1.17, 95% CI 1.04, 1.35. Over-estimation was highest in women ages 50–69 years (E/O=1.29, 95% CI 1.03, 1.69), and for those in the top quartile of risk. Overall discrimination was fair with a c-statistic of 0.66 (95% CI 0.63, 0.70). Further, when using different 10-year risk eligibility thresholds most cases would have been missed in the 30–49 age group using the 8% 10-year risk threshold, while relatively few women aged 50–69 would have been ineligible at any of the thresholds examined.
Conclusion
We found IBIS over-estimates the risk of breast cancer in this screening cohort but has adequate discrimination. Age-specific risk thresholds should be considered to optimize Program eligibility criteria.
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Article info
Publication history
Accepted:
March 5,
2023
Received in revised form:
March 4,
2023
Received:
July 4,
2022
Publication stage
In Press Accepted ManuscriptIdentification
Copyright
© 2023 Published by Elsevier Inc. on behalf of American College of Medical Genetics and Genomics.
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