Contralateral mastectomy and survival after breast cancer in carriers of BRCA1 and BRCA2 mutations: retrospective analysisBMJ 2014; 348 doi: https://doi.org/10.1136/bmj.g226 (Published 11 February 2014) Cite this as: BMJ 2014;348:g226
- Kelly Metcalfe, professor1, adjunct scientist2,
- Shelley Gershman, registered nurse12,
- Parviz Ghadirian, professor3,
- Henry T Lynch, professor4,
- Carrie Snyder, registered nurse4,
- Nadine Tung, associate professor5,
- Charmaine Kim-Sing, professor6,
- Andrea Eisen, medical oncologist7,
- William D Foulkes, professor8,
- Barry Rosen, associate professor9,
- Ping Sun, statistician2,
- Steven A Narod, professor2
- 1Lawrence S Bloomberg Faculty of Nursing, University of Toronto, Canada
- 2Women’s College Research Institute, M5G 1N8 Toronto, Canada
- 3Epidemiology Research Unit, Centre Hospitalier de Université de Montreal, Montreal, Canada
- 4Department of Preventive Medicine and Public Health, Creighton University School of Medicine, Omaha, NE, USA
- 5Beth Israel Deaconess Medical Center, Boston, MA, USA
- 6BC Cancer Agency, Vancouver, Canada
- 7Toronto Sunnybrook Regional Cancer Center, Toronto, Canada
- 8Program in Cancer Genetics, McGill University, Montreal, Canada
- 9University Health Network, Toronto, Canada
- Correspondence to: S A Narod
Objective To compare the survival rates of women with BRCA associated breast cancer who did and did not undergo mastectomy of the contralateral breast.
Design Retrospective analysis.
Setting 12 cancer genetics clinics.
Participants 390 women with a family history of stage I or II breast cancer who were carriers of BRCA1 and BRCA2 mutations and initially treated with unilateral or bilateral mastectomy. 181 patients had mastectomy of the contralateral breast. Patients were followed for up to 20 years from diagnosis.
Main outcome measure Death from breast cancer.
Results 79 women died of breast cancer in the follow-up period (18 in the bilateral mastectomy group and 61 in the unilateral mastectomy group). The median follow-up time was 14.3 years (range 0.1-20.0 years). At 20 years the survival rate for women who had mastectomy of the contralateral breast was 88% (95% confidence interval 83% to 93%) and for those who did not was 66% (59% to 73%). In a multivariable analysis, controlling for age at diagnosis, year of diagnosis, treatment, and other prognostic features, contralateral mastectomy was associated with a 48% reduction in death from breast cancer (hazard ratio 0.52, 95% confidence interval 0.29 to 0.93; P=0.03). In a propensity score adjusted analysis of 79 matched pairs, the association was not significant (0.60, 0.34 to 1.06; P=0.08). Based on these results, we predict that of 100 women treated with contralateral mastectomy, 87 will be alive at 20 years compared with 66 of 100 women treated with unilateral mastectomy.
Conclusions This study suggests that women who are positive for BRCA mutations and who are treated for stage I or II breast cancer with bilateral mastectomy are less likely to die from breast cancer than women who are treated with unilateral mastectomy. Given the small number of events in this cohort, further research is required to confirm these findings.
Contributors: KM and SAN conceived and planned the study and drafted the manuscript. SG collected and coordinated the data. PS performed all data analysis. HTL, PG, NT, CK-S, CS, AE, WDF, and BR coordinated research activities at their respective institutions. All authors read and approved the final manuscript. KM and SAN are the guarantors.
Funding: This research was funded by the Canadian Breast Cancer Foundation (Ontario Chapter). KM is supported by the Canadian Institutes of Health Research and the Ontario Women’s Health Council.
Competing interests: All authors have completed the ICMJE uniform disclosure form at www.icmje.org/coi_disclosure.pdf and declare: no support from any organisation for the submitted work; no financial relationships with any organisations that might have an interest in the submitted work in the previous three years; no other relationships or activities that could appear to have influenced the submitted work.
Ethical approval: This research was approved by the research ethics boards of all Womens College Research Institute (institutional review board approval No 2007-0075).
Data sharing: No additional data available.
Transparency: The lead author affirms that this manuscript is an honest, accurate and transparent account of the study being reported; that no important aspects of the study have been omitted; and that any discrepancies from the study as planned (and, if relevant, registered) have been explained.
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