Wednesday, December 26, 2007

Highest Breast Cancer Risk! Hispanic women.......and Men!

In the December 26th issue of the Journal of the American Medical Association an article caught my eye. It turns out that Hispanic women(and men) have the highest carrier rate for BRCA1 mutations aside from the Ashkenazi Jewish population.

The study sought to identify carrier rates among several different ethnicities. This is important because traditionally we have had little data on women of color as well a worse outcomes in African American and Hispanic women with breast cancer. There have been several hypotheses for this.

This study performed by the Northern California Cancer Center had methods of design where they sought "patients younger than 65 years with newly diagnosed breast cancer and meeting defined eligibility criteria, and their family members, were enrolled

This analysis is based on women diagnosed with invasive breast cancer between January 1, 1995, and December 31, 2003. Patients were identified through the population-based Greater San Francisco Bay Area Cancer Registry, which ascertains all incident cancers as part of the SEER (Surveillance, Epidemiology, and End Results) program and the California Cancer Registry.

We recruited patients with oversampling of patients having characteristics suggesting an inherited basis for their cancers.

In stage 1 of sampling, we administered a brief telephone interview to all patients and assessed self-identified race/ethnicity and family history of breast and ovarian cancer.

In stage 2, we invited all patients in category A and a random sample of patients in category B (2.5% of non-Hispanic whites and 33% of all other races/ethnicities) to enroll in the family registry.

Participants completed questionnaires on family history of cancer and breast cancer risk factors and provided a biospecimen sample.

This 2-stage sampling design provides unbiased estimates of mutation carrier prevalence having greater precision than those obtained from a simple random sample of the same size.

What did they find?

Among African American, Asian American, and Hispanic patients in the Northern California Breast Cancer Family Registry, the prevalence of BRCA1 mutation carriers was highest in Hispanics and lowest in Asian Americans. The higher carrier prevalence in Hispanics may reflect the presence of unrecognized Jewish ancestry in this population.

In the editorial after it states a similar quandary

What are the reasons women are not offered genetic counseling and testing as part of a comprehensive risk assessment program? Are minority patients less likely to accept genetic counseling, or are there barriers to physicians offering the test to minority women? A recent case-control study found that African American women were 78% less likely to use genetic counseling and BRCA genetic testing than white women. Data on BRCA testing from Myriad Genetics Laboratories showed that less than 10% of individuals tested were from minority populations, such as Hispanics, African Americans, Asian Americans, and Native Americans.

Given that most literature on genetic testing has focused on Ashkenazi Jewish and non-Hispanic white women, it is conceivable that clinicians are not aware of the clinical usefulness of BRCA testing among US minority populations. To compound the problem, most of the available risk assessment tools were developed using empirical data collected mainly in non-Hispanic white populations. Their applicability in other populations is uncertain. Other models were developed based on mendelian principles and the Bayes theorem. Of these, the BRCAPRO model has been widely used in the genetic counseling setting, and its performance has been evaluated mostly in white populations. However, as an essential parameter of the BRCAPRO model, the prevalence of mutation carriers is available only for the Ashkenazi Jewish and non-Hispanic white populations.

The Sherpa Says:

If you are using the Gail are putting yourself at risk for missing cases. In addition, not all BRCA carriers are Ashkenazi. Maybe insurers need to wise up and start covering testing for other ethnicities as easily as they do for the Ashkenazim. However, these data must be interpreted with caution as they assume the penetrance of the BRCA1 to be the same in minority patients as they are in Caucasians. In addition, there is no analysis of BRCA2 carriers. But this is a great starting point.


GenEus said...

Yet the findings specifically state that "the prevalence of BRCA1 mutation carriers was highest in Hispanics and lowest in Asian Americans. The higher carrier prevalence in Hispanics may reflect the presence of unrecognized Jewish ancestry in this population." Sort of is contradictory to your statement.

Interestingly, those of us who know Jewish history "from the inside," so to speak, are not surprised by these findings. Historical events occuring in Iberia 500 years ago lead some historians to believe that a high percentage of hispanics (descended from Spain) share some Jewish ancestry. The high prevalence of BRCA1 mutations is therefore not surprising.

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