Penetrance estimates for BRCA1 and BRCA2 based on genetic testing in a Clinical Cancer Genetics service setting: Risks of breast/ovarian cancer quoted should reflect the cancer burden in the family
2008

Cancer Risks for BRCA1 and BRCA2 Mutation Carriers

Sample size: 385 publication Evidence: high

Author Information

Author(s): Evans D Gareth, Shenton Andrew, Woodward Emma, Lalloo Fiona, Howell Anthony, Maher Eamonn R

Primary Institution: Academic Unit of Medical Genetics and Regional Genetics Service, St Mary's Hospital Manchester

Hypothesis

What are the cancer risks for women with BRCA1 and BRCA2 mutations in high-risk families?

Conclusion

Women who test positive for BRCA1 or BRCA2 mutations in high-risk families have significant cumulative breast and ovarian cancer risks.

Supporting Evidence

  • Breast cancer penetrance for BRCA1 was 68% by age 70.
  • Ovarian cancer risk for BRCA1 was 60% by age 70.
  • Women born after 1940 had a cumulative breast cancer risk of 22% by age 40.

Takeaway

If a woman has a family history of breast or ovarian cancer and tests positive for a BRCA mutation, she has a high chance of getting those cancers.

Methodology

The study reviewed 385 families with BRCA1 and BRCA2 mutations and estimated cancer risks based on genetic testing.

Potential Biases

Potential bias from women having prior knowledge of their mutation status before testing.

Limitations

The study may have biases related to family ascertainment and the effects of modifier genes were not fully accounted for.

Participant Demographics

The study included women from high-risk families with BRCA1 and BRCA2 mutations.

Statistical Information

P-Value

p = 0.0005

Confidence Interval

95%CI 64.7–71.3% for BRCA1 breast cancer risk

Statistical Significance

p<0.05

Digital Object Identifier (DOI)

10.1186/1471-2407-8-155

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