Genetic Assessment of Breast Cancer Risk in Women in the DORA Programme

This study is a continuation of a previous study conducted within the Slovenian DORA breast cancer screening programme. The previous study included women who turned 50 years of age in 2021, were invited for their first screening mammography in the DORA programme, completed a breast cancer risk questionnaire, and provided informed consent.

In the previous study, breast cancer risk was initially estimated using the S-IBIS model on the basis of questionnaire data and mammographic information. A total of 291 women were identified as having moderately increased or high breast cancer risk. Because the initial assessment was based mainly on self-reported information and did not include expert-assisted verification of all risk factors and family cancer history, these women are invited to participate in a more detailed risk assessment.

Participants who provide consent complete additional questionnaires and attend an individual consultation at the Department of Clinical Cancer Genetics of the Institute of Oncology Ljubljana. During the consultation, personal breast cancer risk factors and family cancer history are reviewed with a specialist. Reported cancer diagnoses in family members are verified, where possible, using the Slovenian Cancer Registry. Information collected includes personal characteristics, breast cancer risk factors, family history of cancer, breast tissue density, and genetic test results when genetic testing is performed.

Individual breast cancer risk is reassessed using the S-IBIS and CanRisk models. Genetic testing is offered when the participant meets the criteria defined in the applicable clinical guidelines. Following completion of the assessment, each participant receives recommendations for further breast cancer screening and follow-up according to her reassessed level of risk.

The study hypothesis is that more than half of the women initially classified as having increased breast cancer risk will be reclassified as having population-level risk after the detailed reassessment. The primary objective is to provide women who remain at moderately increased or high risk with more appropriate risk-adapted screening and follow-up. The secondary objective is to evaluate agreement between breast cancer risk estimates obtained using the S-IBIS and CanRisk models.

The study includes women previously classified as having moderately increased or high breast cancer risk. Women with a diagnosis of breast cancer are excluded. Data will be analyzed using descriptive statistical methods and will be processed in a pseudonymized form.

• Comprehensive Clinical and Genetic Breast Cancer Risk Assessment (Other): Participants receive an individual clinical and genetic breast cancer risk assessment. Personal risk factors are reviewed with the assistance of a specialist, and family cancer history is verified using the Slovenian Cancer Registry. Breast cancer risk is calculated using the S-IBIS and CanRisk models. Genetic counseling is provided, and genetic testing is performed when the participant meets the applicable clinical criteria. Recommendations for screening and follow-up are adapted to the reassessed level of breast cancer risk.

Primary outcomes

• Proportion of Participants Reclassified to Population-Level Breast Cancer Risk [Through study completion, up to 34 months]: The number of participants previously classified as having moderately increased or high breast cancer risk who are reclassified as having population-level risk after the comprehensive reassessment will be divided by the total number of participants who complete the reassessment and expressed as a percentage. The comprehensive reassessment includes specialist-assisted review of personal breast cancer risk factors, verification of family cancer history, breast cancer risk calculation using the S-IBIS and CanRisk models, and genetic test results when available.

Secondary outcomes

• Agreement Between S-IBIS and CanRisk Breast Cancer Risk Classifications [Through study completion, up to 34 months]: The number and percentage of participants assigned to the same breast cancer risk category by the S-IBIS and CanRisk models will be reported. The evaluated categories are population-level risk, moderately increased risk, and high risk. The same available participant data will be used for both risk calculations.

Sex: Female, ages: 53 Years to 54 Years

Inclusion Criteria:

\- Women who participated in the previous DORA study and were classified by the S-IBIS model as having moderately increased or high breast cancer risk.

Exclusion Criteria:

* Diagnosis of breast cancer.