Breast Cancer Risk Associated With Wealth

Dec. 1, 2005 — -- Women who live in regions of the United States known as breast cancer "hot spots" may have an increased risk because of personal wealth and not pollution or electrical wires, researchers say.

Deborah Winn, a scientist with the National Institutes of Health, states in the December issue of the journal Nature Reviews Cancer that the most likely reason that women in certain communities -- such as Long Island or San Francisco -- have increased breast cancer risk is that those areas are populated by wealthy women. Winn's article analyzes a series of studies conducted by the Long Island Breast Cancer Study Project in New York.

These women tend to have children later, have fewer children, and are more likely to receive costly replacement hormone therapy -- all of which are linked to increased breast cancer risk.

Or, put another way, these women tend to have more estrogen circulating in their bodies for longer periods of time. Estrogen is highly associated with breast cancer. The widely used breast cancer drug Tamoxifen is used to suppress circulating estrogen.

It had been theorized that women in Long Island were at risk because they lived near hazardous-chemical sites or powerful electrical plants. This indeed may be at play, but "measuring environmental exposures that occurred in the past is very difficult," Winn's article notes.

Plus, lifestyle factors and genetics often are involved, too, compounding the challenge of finding one dominant risk factor.

For example, some clusters of breast cancer may be due in part to a higher percentage of Jewish women living on Long Island, said Tulane University environmental health professor Charles Miller. Women of Ashkenazi Jewish descent are more likely to carry breast cancer gene mutations. Many Ashkenazi Jews, or descendants of Jews from Germany and Central Europe, live on Long Island.

"I would expect that a GIS plot (map) of the population density of Jewish women might correspond well to the patterns of excess breast cancer incidence shown in the national map," Miller said.

However, it's important to note that the Nature article does not rule out possible environmental contributions to breast cancer risk, said Mary Wolff, acting director of Mount Sinai School of Medicine's Division of Epidemiology.

Wolff said that environmental causes of breast cancer risk may start 20 years to 40 years before diagnosis, so studies that look for chemical exposure at the time of a woman's diagnosis are too late to catch the culprit.

The Long Island Breast Cancer Study Project is now examining whether early life exposure contributes to breast cancer risk.

In the meantime, most experts feel that the biggest factors in cancer risk are personal, not environmental, such as smoking and sexual activity. Smoking is a known risk factor for lung cancer, and cervical cancer is caused by a sexually transmitted disease.

"I believe the take-home message to the public should be that cancer risks in the U.S. today are largely determined by personal habits, not external environmental factors," said Charles H. Hennekens, of the Epidemiology and Public Health Department at the University of Miami School of Medicine.