Most inherited cases of breast cancer are associated with one of two abnormal genes: BRCA1 (BReast CAncer gene one) or BRCA2 (BReast CAncer gene two).
Women with an abnormal BRCA1 or BRCA2 gene:
- have up to an 85% lifetime risk of developing breast cancer
- have a much higher-than-average lifetime risk of ovarian cancer; estimates range from 15% to 60%
A study presented at the September 2011 Multidisciplinary Breast Cancer Symposium suggests that women diagnosed with breast or ovarian cancer linked to an inherited abnormal breast cancer gene are younger when diagnosed compared to their older relatives.
Researchers compared the average age at diagnosis of 132 women diagnosed between 2003 and 2009 with cancer linked to an inherited abnormal BRCA gene to the average age at diagnosis of one or more of their older relatives who also were diagnosed with cancer linked to an abnormal BRCA gene.
In the older generation, half the women were diagnosed younger than 48 and half were diagnosed at an older age.
In the younger generation, half the women were diagnosed younger than 42 and half were diagnosed at an older age.
Doctors refer to this pattern of younger diagnosis of cancer linked to an inherited abnormal BRCA gene as anticipation. Other research also has found that anticipation happens, but experts aren't sure why. Besides cancer being diagnosed at an earlier age in the younger generation, anticipation also seems to mean the cancer is more aggressive in the younger generation compared to the older generation.
The American Cancer Society recommends that women with an abnormal breast cancer gene start breast cancer screening at age 25 (compared to age 40 for women with an average risk of breast cancer). Anticipation makes starting screening this young very reasonable and important. Experts think that if anticipation continues in future generations, women with an abnormal BRCA1 or BRCA2 gene will be diagnosed at even younger ages. So starting screening at an even earlier age may need to be considered in the future.
If you or a relative have an abnormal breast cancer gene, it's important that you work closely with your doctor to get the testing and regular screening that's best for your situation. You can learn more about abnormal BRCA1 and BRCA2 gene on the Breastcancer.org Breast Cancer Risk Factors: Genetics page.