Treatment Delay and Genetics May Affect Breast Cancer Prognosis in Hispanic Women

Roxanne Nelson

February 09, 2009

February 9, 2009 (Carefree, Arizona) — The incidence of breast cancer and related mortality rates are lower in Hispanic women than in non-Hispanic white women, but the profile of tumor presentation among Hispanic women is consistent with a more aggressive disease pattern and a less favorable prognosis.

Here at the American Association for Cancer Research Science of Cancer Health Disparities Conference, researchers report that this paradox might be partly due to late detection; study results showed a delay in seeking medical care. A second study also showed that there is an increased risk for triple-negative breast cancer among those with a family history of the disease.

"The problem of breast cancer is very poorly understood in this population, and it's an issue that affects the [United States] because of the large and growing population of Hispanics in this country," said Elena Martinez, PhD, professor of epidemiology at the University of Arizona Mel and Enid Zuckerman College of Public Health, in Tucson. Dr. Martinez moderated the press briefing at which the data were presented.

The study data were drawn from the ELLA Binational Breast Cancer Study, a multicenter collaboration between the United States and Mexico. The goal of the collaboration is to determine whether epidemiologic and clinical risk factors, as well as standard and novel tumor markers, which predict incidence and prognosis of breast cancer, differ between women in Mexico and Mexican-American women living in the United States.

"We have been able to look at risk factors of women on both sides of the border," said Dr. Martinez, who is also a coinvestigator in the ELLA study. "We are comparing a variety of clinical factors and reproductive factors."

Delay in Medical Care, High Incidence of Self-Detection

In the first study, lead author Rachel Zenuk, a graduate student at the University of Arizona Mel and Enid Zuckerman College of Public Health, explained that a high percentage of cancers are not being detected by mammography but, instead, are being detected by self exam.

"We also found that many women waited more than a month to seek medical attention," she said. "A third of patients said that they didn't have medical insurance or that they couldn't afford it, and a third didn't think it was important."

The American cohort of the ELLA study was comprised of 230 breast cancer patients of Mexican descent, aged 40 years or older. Education level, exposure to English-language media, and whether or not the woman was born in the United States played a role in the use of mammography.

The most common method of breast cancer detection was self-detection (67%), followed by screening mammography (23%), clinical exam by a health professional (6%), and other methods (3%). Among patients born in the United States, however, 83% reported having undergone a previous mammogram, compared with 62% of non-American-born women. Women with at least a high school diploma were more likely to have undergone previous mammography (76% vs 62%), as were women who had frequent exposure to English-language radio and television programming (77% vs 58%).

The researchers also found that delays in seeking medical care were common in this population. Nearly half (49%) of the women reported that they waited a month or longer before seeking medical care after detecting a breast abnormality. The most common reasons given were lack of health insurance or not being able to afford medical care (36%), or feeling it was unimportant (27%).

Triple-Negative Breast Cancer

In the second study, researchers assessed the association between family history and tumor subtype within ethnic groups. Results of a previous study suggested that family history was significantly associated with estrogen-receptor-negative tumors among Hispanic women, but a similar relationship had not been observed among non-Hispanic whites.

Researchers found that the odds of a family history of triple-negative breast cancer were higher in Mexican American women, but not black women, explained author Betsy C. Wertheim, MS, assistant scientific investigator in the Cancer Prevention and Control Program at the Arizona Cancer Center, in Tucson.

But the increased risk among Hispanic women was primarily observed in those born in Mexico. "And this significant association was driven entirely by women who lived in Arizona and wasn't seen in those living in Texas," she said.

Ms. Wertheim and colleagues used data on 260 Mexican American women from the ELLA study and a parallel dataset of 206 black women from University of Texas MD Anderson Cancer Center, in Houston. Family history was defined as a self-reported history of breast or ovarian cancer in a relative younger than 50 years.

Compared with black women, the Hispanic women in this study who had a family history of breast cancer had a 2.2-fold increased risk for triple-negative breast cancer. The women with triple-negative breast cancer were also diagnosed with the disease at a significantly younger age.

These are preliminary findings, Ms. Wertheim emphasized, but the association appears to be driven by geography and a combination of genetics and environment.

The researchers also note a strong association between family history and triple-negative breast cancers in this specific population, which suggests that the presence of BRCA mutations account for a higher proportion of breast cancers in young Mexican American women.

American Association for Cancer Research Science of Cancer Health Disparities Conference: Abstracts PR-4 and A55. Presented February 4, 2009.

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