Hereditary Breast Cancer

Familial Breast Cancer

A family history of breast cancer has been consistently recognized as one of the most important risk factors for the disease. Various studies have suggested that between 15-25% of women with breast cancer have at least one first- or second-degree relative who also has breast cancer. A woman with an affected first-degree relative has from 1.5-2.5 times the breast cancer risk of a woman without a family history of breast cancer. Within the group of women with a family history of breast cancer, those with multiple affected relatives are at higher risk, as are those with relatives affected at younger ages.

Risk is also higher in some, but not all, series if one or more of the affected relatives has had bilateral disease. Because relative risk figures may be difficult to translate in a meaningful way when performing clinical risk counseling, empirical models have been developed that can be used to provide women with an estimated percentage risk of developing breast cancer over a defined time period. The best known models are the "Claus tables" and the Gail model.

The "Claus tables" derive from the Cancer and Steroid Hormone Study (CASH) dataset, and only use family history data to generate risk figures.

The Gail model, generated from the Breast Cancer Detection Demonstration Project dataset, incorporates reproductive and clinical variables in addition to a history of breast cancer in first-degree relatives (mothers and sisters). Both models are useful, but have significant limitations when used to estimate individual cancer risks.

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Mark E. Robson
Breast conservation therapy for invasive breast cancer in Ashkenazi women with BRCA gene founder mutations. J Natl Cancer Inst 2003

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