Dutch Study Questions Amount Family History Increases Risk

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A study looked at the health histories of more than 800 women diagnosed with breast cancer and almost 2,000 sisters of these women. The research is part of a large study called PROSPECT, which is following the health histories of more than 17,000 women in Holland.

The researchers found that having a first-degree relative (a mother or a sister) diagnosed with breast cancer increases breast cancer risk. But, this higher risk may not be as high as it is thought to be. This is especially true for breast cancer diagnosed before age 50. The results suggest that starting aggressive breast cancer screening before age 50 in women who had a sister diagnosed with breast cancer may not make sense.

About 25% of the women in the study had one or more of the following risk factors:

  • at least two cases of breast cancer in first-degree female relatives
  • at least two cases of breast cancer in first- or second-degree female relatives younger than 50
  • at least one case of breast cancer in a first- or second-degree female relative younger than 40
  • a female relative diagnosed with bilateral breast cancer (breast cancer in both breasts)

About 33% of the women in the study diagnosed with breast cancer had a least one of these family health risk factors. The younger a woman was when diagnosed, the more likely she was to have at least one of the risk factors:

  • 40% of the women diagnosed with breast cancer younger than 50 had at least one family health risk factor
  • 60% of the women diagnosed with breast cancer younger than 30 had at least one family health risk factor

Still, when the researchers looked at a woman's risk of developing breast cancer when she had at least one family health risk factor, the risk was fairly low, especially for developing breast cancer younger than 30.

A woman with one family health risk factor had the following risk:

  • 0.5% of developing breast cancer younger than 30
  • 4% of developing breast cancer younger than 50
  • 8% of developing breast cancer younger than 70
A woman with two family health risk factors had the following risk:
  • 0.9% of developing breast cancer younger than 30
  • 11% of developing breast cancer younger than 50
  • 13% of developing breast cancer younger than 70

Doctors who specialize in determining risk and disease screening make recommendations about who should be screened and when they should be screened. To make these recommendations, the doctors compare screening's benefits to its costs and risks. Costs and risks of screening include the risk of more procedures and tests (and the worry that comes with them) if screening suggests a problem when nothing is wrong.

The benefits of breast cancer screening outweigh the costs and risks for all women older than 50. It's less clear if women younger than 50 get more benefit than risk from aggressive breast cancer screening. In this study, breast cancer risk was higher (and increased more) for breast cancer diagnosed older than 50. So the researchers concluded that starting aggressive breast cancer screening in younger women with one or more family health risk factor may not make sense.

If you have one or more relatives who've been diagnosed with breast cancer, you'll want to do all that you can to reduce your risk of breast cancer. If you've been diagnosed with breast cancer, you want to make sure it's diagnosed as early as possible. You'll also want to make sure that your relatives do all they can to reduce their own risk. No matter how old you are, it's a good idea to work with your doctor to decide on a breast cancer screening approach that makes the most sense for you and your family and your unique situation. Your doctor will probably consider:

  • how old people in your family were when diagnosed with breast cancer
  • the type and aggressiveness of breast cancer diagnosed in your family
  • any family history of an abnormal breast cancer gene
  • any family history of ovarian cancer (ovarian cancer increases breast cancer risk)

The breast cancer screening plan you and your doctor develop might include:

  • starting screening at an earlier age and screening more than once a year
  • adding other screening techniques, such as ultrasound and MRI, to an annual mammogram
  • genetic counseling and genetic testing because abnormal BRCA1 and BRCA2 genes are more likely with a strong family history of breast cancer
  • screening for ovarian cancer

Visit the Breastcancer.org Lower Your Risk section to learn more about breast cancer risk and what you can do to keep your risk as low as it can be.

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