Family history of breast cancer may not mean early onset breast cancer

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Applying family history-related criteria in an unselected population could result in the screening of many women who will not develop breast cancer at an early age, according to a study published in the July 23 issue of BMC Cancer.

An increased risk of breast cancer for relatives of breast cancer patients has been demonstrated in many studies, and having a relative diagnosed with breast cancer at an early age is an indication for breast cancer screening, according to researchers. The indication has been derived from estimates based on data from cancer-prone families or from BRCA1/2 mutation families, and might be biased because BRCA1/2 mutations explain only a small proportion of the familial clustering of breast cancer.

Geertruida H. De Bock from department of epidemiology at the Groningen University Medical Center in Groningen, the Netherlands, and colleagues said the aim of the study was to determine the predictive value of a family history of cancer with regard to early onset of female breast cancer in a population-based setting.

The researchers said that they studied an unselected sample of 1,987 women with and without breast cancer with regard to the age of diagnosis of breast cancer.

The investigators found that the risk of early-onset breast cancer was increased when there were: (1) at least two cases of female breast cancer in first-degree relatives; (2) at least two cases of female breast cancer in first or second-degree relatives under the age of 50; (3) at least one case of female breast cancer under the age of 40 in a first- or second-degree relative; and (4) any case of bilateral breast.

De Bock and colleagues said that the positive predictive value of having two or more of the characteristics was 13 percent for breast cancer before the age of 70, 11 percent for breast cancer before the age of 50 and 1 percent for breast cancer before the age of 30.

Based on their findings, the authors concluded that “applying family history related criteria could result in the screening of many women who will not develop breast cancer at an early age.” Chances of developing early breast cancer are very small, when there is limited family history for breast cancer and none or only one of the four criteria is applicable, according to the researchers.