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Breast Cancer Research and Treatment

, Volume 167, Issue 1, pp 263–267 | Cite as

The expected benefit of preventive mastectomy on breast cancer incidence and mortality in BRCA mutation carriers, by age at mastectomy

  • Vasily Giannakeas
  • Steven A. Narod
Epidemiology

Abstract

Purpose

Preventive breast surgery is offered to unaffected BRCA mutation carriers to prevent breast cancer incidence and mortality. The clinical benefit of preventive mastectomy can be measured in several ways, including extension of life expectancy (mean years of life gained) and by estimating the probability of surviving until age 80. We sought to estimate the expected benefit of a preventive mastectomy at various ages, using these indices of mortality, by simulating hypothetical cohorts of women.

Methods

The age-specific annual risks of developing breast cancer were used to estimate the actuarial risk of developing breast cancer by age 80 for women with a BRCA1 or BRCA2 mutation. The probability of developing breast cancer before age 80 was then modified to include competing causes of death, including from ovarian cancer. The mortality rate from breast cancer after a diagnosis of breast cancer was set at 2% annually for the first 10 years and then 1% annually for years ten to twenty. The incidence rate and mortality rate from ovarian cancer were based on published literature. We assumed that preventive mastectomy was associated with complete protection against subsequent breast cancer. A series of simulations was conducted to evaluate the reduction in the probability of death (from all causes) until age 80, according to the age at mastectomy.

Results

The actuarial risk of developing breast cancer until age 80 was estimated to be 70.8%. The actual risk (incorporating competing risks) was 64.0%. The probability of being alive at age 80 by having a mastectomy at age 25 increased by 8.7% (from 42.7 to 51.3%). The estimated benefit declined with age at mastectomy; for surgery done at age 50 the improvement in survival to age 80 was much more modest (2.8% at age 80, from 42.7 to 45.5%).

Conclusions

Among BRCA mutation carriers, the mortality benefit of preventive mastectomy at age 25 is substantial, but the expected benefit declines rapidly with increasing age at surgery.

Keywords

BRCA Breast cancer Ovarian cancer Mastectomy 

Notes

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

Ethical approval

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. This article does not contain any studies with animals performed by any of the author.

Informed consent

Informed consent was obtained from all individual participants included in the study.

Supplementary material

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Supplementary material 1 (DOCX 13 kb)
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Supplementary material 2 (JPEG 43 kb)
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Supplementary material 3 (JPEG 47 kb)
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Supplementary material 4 (JPEG 55 kb)

References

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Copyright information

© Springer Science+Business Media, LLC 2017

Authors and Affiliations

  1. 1.Women’s College Research Institute, Women’s College HospitalTorontoCanada
  2. 2.Dalla Lana School of Public HealthUniversity of TorontoTorontoCanada

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