Age-specific risks of incident, contralateral and ipsilateral breast cancer among 1776 Polish BRCA1 mutation carriers
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Women with an inherited germline BRCA1 mutation have a high lifetime risk of developing breast cancer. We have previously shown that, among BRCA mutation carriers, incidence rates of breast cancer vary by country of residence.
In the current study, we prospectively calculated the cumulative and annual incidence rates of incident breast cancer, contralateral breast cancer and ipsilateral breast cancer recurrence among BRCA1 mutation carriers in Poland. Study subjects comprised a cohort of 1776 Polish women with a BRCA1 mutation who had no prior diagnosis of breast or ovarian cancer at the time of enrollment, the women were followed with a biennial follow-up by questionnaire. Women were followed for an average of 6.1 years (range 0.0–18.2) and 191 new breast cancer cases were diagnosed.
The cumulative incidence of breast cancer to age 70 was 52%. The annual risk of breast cancer was estimated at 1.78%; the maximum annual risk was observed between the ages of 30 and 65. Among the 941 women with a prior diagnosis of breast cancer, 106 women developed a contralateral breast cancer. The 20-year cumulative incidence of contralateral breast cancer was 31% and the annual rate of contralateral breast cancer was 1.96%. There were 11 recurrences among the 215 women with breast cancer (ipsilateral breast cancers). The cumulative incidence at 20 years was 17% and the annual rate of an ipsilateral recurrence was 1.03%.
Our findings confirm the high annual rates of early-onset incident, contralateral and recurrent breast cancer among Polish BRCA1 mutation carriers. These risk estimates are important in the context of the clinical management of unaffected women as well as in the treatment of newly diagnosed primary breast cancers and can also be used as the basis for the planning of prevention trials.
KeywordsBRCA1 Breast cancer Poland
We would like to acknowledge the study staff, students, and volunteers including Shana Kim, Farah Shoukat, Ellen MacDougall, Zoella Pasta, Nida Mian, Jennifer Ng, Sarah Chin, Hamida Begum, Harmeet Chaudhary, Asrafi Azmi, Shahana Nargis, Clotilde Ngwa, Mai Abdelhadi, Saiveena Penikalapati, Laavanya Somasundaram, and Hannah Horvath who helped with the data collection and data entry.
Joanne Kotsopoulos is a recipient of a Tier II Canada Research Chair. Steven A. Narod is the recipient of a Tier I Canada Research Chair. This study was supported by a Canadian Cancer Society Research Institute grant (703058) and the Peter Gilgan Foundation.
Compliance with ethical standards
Conflict of interest
All authors declare they have no conflict of interest.
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
Informed consent was obtained from all individual participants included in the study.
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