Cancer Advances: BRCA Mutations Among Asian-American Women May Be More Common than Predicted

Posted online September 9, 2008, on www.jco.org.

Researchers from the U.S. and Canada found that two computer models widely used to determine who should undergo genetic testing for BRCA mutations underpredicted mutation frequency in Asian-American women by 50 percent. Mutations in the BRCA1 and BRCA2 genes significantly increase the risk of breast and ovarian cancers, and women who learn they have these mutations are encouraged to seek more frequent cancer screening or may undertake other measures to reduce their cancer risk, such as preventive mastectomy or removal of the ovaries.

The incidence of breast cancer among Asians is generally lower than among Caucasians. However, breast cancer rates are increasing in China, Korea and other Asian countries and among Asian immigrants to the United States, which has led to increasing demand for BRCA1/2 mutation testing.

The models, called BRCAPRO and Myriad II, are commonly used to determine which patients inquiring about genetic consultation would benefit most from genetic testing for BRCA mutations. These models were initially created using data on BRCA mutations in Caucasians, and have accurately predicted gene mutation risk in other minority groups.

For this study, researchers compared the results of the BRCAPRO and Myriad II computer prediction models with the findings of genetic testing in 200 Asian-Americans and 200 matched non-Jewish Caucasians. (Jewish women were excluded from the analysis because of their higher prevalence of BRCA mutations.) The models accurately predicted the number of Caucasian BRCA1/2 mutation carriers (25 observed versus 24 predicted by BRCAPRO and 25 by Myriad II). However, the models significantly underpredicted Asian mutation carriers (49 observed versus 25 predicted by BRCAPRO and 26 by Myriad II). For BRCAPRO, the difference was especially pronounced for Asian BRCA2 mutation carriers (26 observed versus only 4 predicted); the Myriad II prediction model does not have the ability to differentiate between BRCA1 and BRCA2 mutation risk.

What This Means for Patients

These findings indicate that Asian-American women with BRCA mutations may not be referred for genetic testing and therefore may not know they have an increased hereditary risk of breast and ovarian cancers. Asian-American women concerned about their risk of these cancers are encouraged to speak with their healthcare providers and to ask whether they should seek consultation with a genetic counselor.

Helpful Links:

• The Genetics of Breast Cancer
• The Genetics of Ovarian Cancer
• Genetic Testing
• What to Expect When Meeting With a Genetic Counselor