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Summary: Breast cancer seems to behave differently in Hispanic women than in white women, even when they get equal care, a new study suggests. According to research findings from the University of Colorado, Hispanic women with breast cancer tend to be younger and to have larger, more advanced tumors. That suggests there may be some biological or genetic determinants in how this disease affects women of different ethnicities, the researchers conclude.

Why it's important: Although breast cancer is less common among Hispanic women than white women, it is still the most commonly diagnosed cancer and the leading cause of cancer death among Hispanic women. Moreover, statistics show that Hispanic women are less likely to be diagnosed with early-stage tumors, which are easier to treat, and more likely to be diagnosed with larger tumors. But even when diagnosed with the same stage tumor at the same age, Hispanic women are more likely to die of breast cancer than white women.

What's already known: No one knows exactly what is behind these differences between Hispanic and white women. One likely cause is that Hispanic women simply don't have access to the same kind of care that white women do. In the US, the poverty rate is higher among Hispanics than whites, and Hispanics are more likely to work in jobs that don't provide health insurance. Those factors could make it harder for Hispanic women to get screened for breast cancer to catch it early, and make it harder for them to get the best treatment if they do get cancer. Another potential issue is that breast cancer might be biologically different in women of different ethnicities or races. Several studies of breast cancer in African-American and white women suggest that there may indeed be some genetic or biological differences.

How this study was done: To find out if the breast cancer differences persisted even when women had the same kind of care, the researchers compared Hispanic and white breast cancer patients in the same insurance plan, Kaiser Permanente Colorado. The women all had access to the same care, including screening with mammography. They had all been diagnosed between 1995 and 2004. The findings were published in the journal Cancer.

What was found: Mammography rates were similar between the Hispanic and white women in the plan. Nevertheless, there were differences in the breast cancer diagnoses. Hispanic women were younger on average (56 vs. 61) at diagnosis, and were more often found to have larger, later-stage tumors. Thirteen percent of Hispanic women had tumors that were 5 cm or larger, compared to just 6.5% of white women. And 6.5% of Hispanic women had stage 4 tumors, the most advanced stage, compared to 2.5% of white women. Hispanic women were also less likely to have tumors with estrogen and progesterone receptors; many effective breast cancer drugs only work on tumors with those receptors.

The researchers were not able to collect information on breast cancer risk factors (such as family history of the disease, weight, the number of children each woman had) so they could not determine if Hispanic women had different characteristics that might have made their breast cancer risk different from that of the white women.

The bottom line: The researchers say their findings lend weight to the idea that biological or genetic factors may be partially to blame for the differences in breast cancer between Hispanic and white women. They're not suggesting economic and social factors aren't important, just that biology may play a role, too. They say more studies should be done to explore the issue.

Of course, women of all ethnicities and races can lower their risk for breast cancer by making certain lifestyle changes. Keeping at a healthy weight, exercising regularly, limiting alcohol, and avoiding hormone therapy after menopause can all help reduce a woman's risk of getting breast cancer. And getting yearly mammograms starting at age 40 is the best way to catch breast cancer early, when treatments are more likely to be successful.

Citation: "Does Having Insurance Affect Differences in Clinical Presentation Between Hispanic and Non-Hispanic White Women with Breast Cancer?" Published online April 9, 2007 in Cancer. First author: A. Tyler Watlington, MD, MSPH, University of Colorado Health Sciences Center, Denver.