Ethnic Gaps in Breast Cancer Linked to Hormones

Ethnic Gaps in Breast Cancer Linked to Hormones

In our efforts to bring you news about Breast Cancer and its available treatments and causes, below please find an article regarding on a recent study that looked at hormone levels as one explanation of the difference in rates of Breast Cancer occurrence in different ethnicities. We have duplicated the full article with a ‘translation’ of the study from BreastCancer.org. We hope this information is helpful to you and your loved ones. – Buttoned Up

NEW YORK (Reuters Health) – Differences in estrogen levels may partially explain the ethnic disparities in breast cancer rates among U.S. women, new research suggests.

In a study of more than 700 postmenopausal women, researchers found that participants’ blood levels of estrogen and “male” hormones, called androgens, varied by race and ethnicity. And the differences in estrogen, which fuels breast tumor growth, often paralleled ethnic differences in breast cancer risk.

Native Hawaiians, for example, had the highest levels of estrogen and androgen, and the highest rate of breast cancer. On average, their estrogen levels were about one-quarter higher than those of white women, according to findings published in the journal Cancer Epidemiology, Biomarkers & Prevention.

Similarly, the study found, women of Japanese descent had higher estrogen levels than white women did, and their breast cancer rate followed suit.

These findings fit the theory that racial or ethnic differences in estrogen levels account for some of the differences seen in breast cancer rates, according to study leader Dr. Veronica Wendy Setiawan of the University of Southern California in Los Angeles.

An exception, she told Reuters Health, was the finding that African-American women had lower rates of breast cancer than white women did, despite having higher estrogen levels.

“We can’t explain that yet,” Setiawan said. It’s known that before menopause, black women have a higher risk of breast cancer than white women, she noted. So it’s a puzzle as to why their risk doesn’t remain elevated after menopause, even though their estrogen levels remain relatively high.

Another finding with no clear explanation is the fact that Japanese-American women had higher estrogen levels and a higher rate of breast cancer than white women did — a stark reversal of what’s been previously observed.

This rise in estrogen levels among Japanese Americans may be driving the rise in breast cancer, according to Setiawan, but no one knows what factors — such as diet or other lifestyle changes — are affecting estrogen levels in these women.

Excess body fat raises estrogen levels, but Japanese Americans in the study were generally thinner than other women.

The findings are based on 739 women who are part of a larger study that has followed an ethnically diverse group of adults from California and Hawaii for more than a decade.

Setiawan notes that more research is needed to figure out why black women differ from other women when it comes to the relationship between estrogen levels and breast cancer — and why estrogen levels appear to be changing among Japanese women.

SOURCE: Cancer Epidemiology, Biomarkers & Prevention, October 2006.

WHAT BREASTCANCER.ORG SAYS:

Ethnic gaps in breast cancer linked to hormones

Research has shown that breast cancer is diagnosed more or less frequently in different ethnic groups in the United States. But scientists aren’t sure why these differences happen. Differences in genetics might be part of the explanation. External factors, such as diet and lifestyle choices, also probably contribute to these differences.

The study reviewed here looked at whether differences in hormone levels could help explain differences in breast cancer rates. While the results don’t provide all the answers, they do offer more information. For example, Japanese American women and native Hawaiian women have a higher than average risk of breast cancer and their estrogen levels were found to be higher than average. On the other hand, African American women have a lower risk of breast cancer than white women, but in this study, African American women had higher estrogen levels than white women.

The study also showed that average estrogen levels of Japanese American women have been rising over time. The reason for this is unclear, and it is not clear that an increase in breast cancer risk will follow.

Stay tuned to Breastcancer.org for the latest updates on this important area.