About 10% of breast cancers are associated with an inherited abnormal gene. Abnormal BRCA1 and BRCA2 genes are the most common inherited breast cancer gene abnormalities. The current guidelines for genetic testing—and whether or not the testing will be covered by insurance—are based on age and a strong family history of breast cancer. It can be important to know if you have an abnormal breast cancer gene; then you and your doctor can develop a more aggressive screening plan (more frequent and starting at an earlier age) or, if you've been diagnosed with breast cancer, a more aggressive treatment and follow-up plan.
A study addresses some of the problems associated with basing approvals for genetic testing on family history. Just how useful is a woman’s family history of breast cancer if her extended family doesn't have very many women in it? Or what if a woman diagnosed with breast cancer has an abnormal gene, and so is at higher risk of developing a new second cancer, but is the first person diagnosed in her family? What if a woman is adopted? The researchers posed these questions while looking at the records of women younger than 50 who were already diagnosed with breast cancer.
The researchers used the term "limited family structure" to describe women in the study who had either 1 or no close living female relatives older than 45. Half of the women studied had a limited family structure. The researchers believe that family history is not useful for these women. Because they have few female relatives, it's likely that these women would not have a strong family history of breast cancer. When the women had genetic testing, the researchers found that women with a limited family structure were more than twice as likely to have a genetic abnormality (about 14%) than women with more than 2 female relatives older than 45 (about 5%).
The results of this study suggest that doctors and insurance companies may need to rethink how important family history is when deciding who should and who shouldn't get genetic testing. A new approach that depends less on family history is probably needed. In the meantime, breastcancer.org agrees with the recommendation that if a woman with breast cancer has fewer than 2 female relatives and is younger than 50, genetic testing is probably reasonable, even if she has no family history. Currently genetic testing is recommended for women younger than 40 who are diagnosed with breast cancer.
To learn more, visit the Breastcancer.org Breast Cancer Risk Factors: Genetics page.
This article was made possible by an educational grant from GlaxoSmithKline.