The study reviewed here suggests that Mexican American women diagnosed with an aggressive type of breast cancer are more likely than African American women diagnosed with the same type of breast cancer to have a family history of breast cancer. The association between the aggressive breast cancer and family history suggests that abnormal breast cancer genes may be more common in Mexican American women.
The study also found that Mexican American women were more likely to have the breast cancer found by breast self-exam rather than by mammogram.
The study, called the ELLA Binational Breast Cancer Study, interviewed more than 650 women of Mexican descent diagnosed with invasive breast cancer. About half of the women lived in the United States and the other half lived in Mexico. The researchers compared the details about each woman's diagnosis, risk factors, and health behaviors to the same information from African American women diagnosed with breast cancer.
The results:
Research on breast cancer specifically in Mexican American and other Hispanic/Latina women has been done less often than research on breast cancer in white and African American women. Research such as the study reviewed here, sometimes called a population study, can help doctors identify patterns of diseases, such as breast cancer, in different groups of people. Population studies also can help explain differences in disease rates or types in different ethnicities of people.
It's good that mammogram rates were high among the Mexican American women in this study. Still, it's troubling that many of the women who found a change in their breasts during self-exam waited a month or more to see a doctor. If you find a change in your breast, talk to your doctor right away. DON'T WAIT. Help is available if you don't have insurance or can't afford the care you need. The thought of cancer is scary, but don't let fear stop you from seeing a doctor. There is only one of you and you deserve the best and most timely care possible.
CAREFREE, Ariz., Jan. 4 (MedPage Today) -- Mexican-American women with breast cancer may be at higher prognostic risk from a one-two punch of genetics and late detection, researchers found.
Mexican-American women diagnosed with triple hormone receptor negative breast cancer were twice as likely as African-American women to have a family history of breast cancer, suggesting BRCA mutation, according to preliminary findings from a binational study led by Elena Martinez, Ph.D., of the University of Arizona and Arizona Cancer Center in Tucson.
The study, reported in multiple presentations here at the American Association for Cancer Research Science of Cancer Health Disparities Conference, also showed that a high percentage of breast cancers in Mexican-American women were detected by palpation rather than screening mammography, suggesting higher stage tumors.
"We feel like we're just at the tip of the iceberg," Dr. Martinez said. "We're just starting to figure out whether the pattern for Hispanic/Latina women is the same as what we know for non-Hispanic white women or African-American women."
Researchers in the ELLA Binational Breast Cancer Study interviewed women of Mexican descent with invasive breast cancer -- 309 living in the United States and 343 living in Mexico -- about their diagnosis, risk factors, and health behaviors.
Established clinical and reproductive risk factors for breast cancer were generally similar between women living in the U.S. and Mexico, although Mexican women were significantly older than those in the U.S. (53.8 versus 48.7 years, P=0.001), had more children (3.7 versus 3.2 live births, P=0.007) and had a lower prevalence of family history of breast cancer (6.2% versus 18.1%, P=0.0001).
Overall, triple-negative disease rates were 28.1% among Mexican women and 19.3% among Mexican-Americans. Reproductive factor data were similar and BMI was high in both countries.
Estrogen-, progesterone-, and HER2/neu-negative tumors are associated with BRCA1 mutation and have a poor prognosis with no targeted therapy, noted Betsy C. Wertheim, also of the Arizona Cancer Center.
In her analysis comparing Mexican-American women in the study -- 138 from Houston and 92 from Arizona -- with data from a parallel cohort of African-American women, Mexican-Americans with triple negative disease were twice as likely to have a family history of breast cancer as those without hormone nonresponsive cancer (age-adjusted hazard ratio 2.02, 95% confidence interval 0.98 to 4.18).
But African American women had no such association (adjusted HR 0.86, 95% CI 0.36 to 2.06).
Among Mexican-American women, the association appeared to be primarily accounted for by those living in Arizona (HR 4.90, 95% CI 1.41 to 17.1, versus 1.43 for Texans, 95% CI 0.55 to 3.70).
Although Wertheim said it was unclear whether this difference was related to environmental exposures or ancestry, she noted that women born outside the U.S. appeared to be driving the association, which suggested that these women have a higher carrier rate of BRCA1 mutations.
Although mammography rates were high among study participants living in the U.S. -- 72% overall -- little of the breast cancer detected among these women was found through screening, reported Rachel Zenuk, a graduate student at the University of Arizona Cancer Center in Tucson.
In her analysis of Mexican-American women, only 22% reported that their breast cancer was found by screening mammography.
The most common method of discovery was breast self-examination (68%). But after noticing a change in their breasts, almost half of the women said they waited at least a month before seeking medical attention.
They cited having no insurance or not being able to afford medical care (31%) and not feeling it was important (33%) as the reason for the delay. Other explanations were fear and no earlier appointments available.
Although the study did not include data on stage at diagnosis, Zenuk noted that a palpable lump or other detectable changes in the breast suggested higher stage tumors.
"Although breast cancer incidence and mortality rates are lower in Hispanic than non-Hispanic white women," Zenuk said based on historical comparisons, "the profile of tumor presentation among Hispanic women is consistent with a more aggressive disease pattern and less favorable prognosis."
Wertheim noted that the study was limited by the small sample size, the case-case design with no control population, and use of family history and other factors as proxies for genetic susceptibility.
The study was initially supported by funding from the National Cancer Institute and the Dove Foundation and is now solely supported by the Dove Foundation.
The researchers reported no conflicts of interest.
Primary source: AACR Science of Cancer Health Disparities Conference Source reference: Zenuk R, et al "Breast cancer detection and screening mammography in Mexican-American women: Findings from the Ella Binational Breast Cancer Study" AACR 2009; A55.Additional source: AACR Science of Cancer Health Disparities ConferenceSource reference: Wertheim BC, et al "Increased odds of family history for triple negative breast cancer in Mexican American but not African American women" AACR 2009; PR4.Additional source: Meza MM, et al "The Ella Binational Breast Cancer Study: Risk factor and tumor marker profile in women of Mexican ancestry" AACR 2009; A78. Source reference: Meza MM, et al "The Ella Binational Breast Cancer Study: Risk factor and tumor marker profile in women of Mexican ancestry" AACR 2009; A78.
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