Introduction Women who have pathogenic mutations in the BRCA1 and BRCA2 genes are at greatly increased risks for breast and ovarian cancers. Although risk-reduction strategies can be undertaken by these women, knowledge regarding the uptake of these strategies is limited. Additionally, the healthcare behaviours of women who receive inconclusive test results are not known. This study protocol describes the creation of a retrospective cohort of women who have undergone genetic testing for BRCA1 and BRCA2, linking genetic test results with administrative data to quantify the uptake of risk-reduction strategies and to assess long-term cancer and non-cancer outcomes after genetic testing.
Methods and analysis Approximately two-thirds of BRCA1 and BRCA2 testing in Ontario, Canada is performed at North York General Hospital (NYGH) and Mount Sinai Hospital (MSH), Toronto. We will use registries at these sites to assemble a cohort of approximately 17 000 adult women who underwent BRCA1 and BRCA2 testing from January 2007 to April 2016. Trained chart abstractors will obtain detailed information for all women tested over this period, including demographics, personal and family cancer histories and genetic test results. We will link these data to provincial administrative databases, enabling assessment of healthcare utilisation and long-term outcomes after testing. Study outcomes will include the uptake of breast cancer screening and prophylactic breast and ovarian surgery, cancer incidence and mortality and incidence of non-cancer health outcomes, including cardiovascular, osteoporotic and neurodegenerative disease.
Ethics and dissemination This study has been approved by the Research Ethics Boards at NYGH (no 16-0035), MSH (no 13-0124) and Sunnybrook Health Sciences Centre (no 275-2016). We plan to disseminate research findings through peer-reviewed publications and presentations at national and international meetings.
- genes BRCA1
- genes, BRCA2
- breast neoplasms
- ovarian neoplasms
- genetic predisposition to disease
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Contributors FD, MCC, RS, KM and NNB contributed to the design of this study. FD, TL, JL-E, AE and WSM participated in the data acquisition. FD, MCC, RS and NNB contributed to developing the analytic plan proposed for this study. FD, TL, JL-E, AE, WSM and NNB were involved in obtaining the ethics approval for this work. FD prepared the first draft of the manuscript. All authors contributed to and approved the final version of the manuscript.
Funding This study is conducted with support from the Canadian Breast Cancer Foundation-Ontario Region (no 316528). This study is also supported by the Institute for Clinical Evaluative Sciences (ICES), which is funded by an annual grant from the Ontario Ministry of Health and Long-Term Care (MOHLTC). This study is supported by the American College of Surgeons Resident Research Scholarship awarded to Drs Fahima Dossa and Maria Cusimano.
Competing interests None declared.
Patient consent Not required.
Ethics approval Mount Sinai Hospital, North York General Hospital, Sunnybrook Health Sciences Centre.
Provenance and peer review Not commissioned; peer reviewed for ethical and funding approval prior to submission.
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