Breast Cancer Genetic Services in a South African Setting: Proband Testing, Cascading and Clinical Management
T S Osler1,2, M Schoeman3, J Edge4
1Sydney Brenner Institute for Molecular Bioscience, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.
Cancer Medicine
|March 5, 2025
Summary
Genetic testing for hereditary breast cancer was well-received by patients in South Africa, but cascade testing uptake by relatives was low. Over half of eligible individuals pursued risk-reducing measures, though uptake varied.
Area of Science:
- Oncology
- Genetics
- Public Health
Background:
- Hereditary breast cancer management data from low- and middle-income countries (LMICs) is scarce.
- Assessing genetic testing and risk-reducing strategies in a South African regional breast cancer service provides crucial insights.
Purpose of the Study:
- To evaluate the effectiveness of proband and cascade genetic testing for hereditary breast cancer.
- To assess the uptake of risk-reducing measures among individuals with hereditary breast cancer in a South African setting.
Main Methods:
- Analysis of records from 534 female breast cancer probands and 115 relatives who received genetic counseling.
- Data collection included demographics, clinical details, family history, and genetic test results.
Main Results:
- Proband genetic testing uptake was high (86.9%), with 19.6% testing positive.
- Cascade testing in relatives was limited (9.2%), but associated with stronger family history and first-degree relation.
- Risk-reducing mastectomy was adopted by 52.6% of eligible women; mammographic surveillance and salpingo-oophorectomy uptake were lower.
Conclusions:
- Genetic testing is accepted by probands, but family member participation (cascade testing) is suboptimal.
- The study identified one family member with a pathogenic variant for every 11 probands tested.
- Variable uptake of cascade testing and risk-reducing options highlights areas for program improvement in LMICs.
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