Washington Post
23 October 2002

Breast Cancer Puzzle in Marin
California County's Rate of Disease Is Almost 40% Higher Than U.S. Norm

By Katherine Ellison
Special to The Washington Post
Page A03

SAN RAFAEL, Calif. -- Marin County, long-famed as a mecca for wealthy hot-tubbers, has recently acquired a darker distinction. Women in these scenic valleys north of San Francisco are being diagnosed with invasive breast cancer at a higher rate than experts have found anywhere else in the United States.

Over the past five years, non-Hispanic white women, the hardest-hit group in this county, have received a diagnosis of breast cancer at a rate nearly 40 percent higher than the national norm. Just as striking is how the rate steadily climbed through the 1990s, increasing 37 percent, compared with 3 percent for the rest of the San Francisco Bay Area.

Marin's predicament has acquired special import in an era when breast cancer rates throughout the developed world have been rising, when more than 40,000 U.S. women are dying of the disease every year, and when scientists increasingly are raising questions about the possible influence of exposure to industrial chemicals. But even as local activists search for environmental smoking guns -- such as links to toxic waste dumps or cellular telephone towers -- experts say women here are most likely vulnerable because of something in this county's lifestyle, rather than in its water.

"We don't think there's strong evidence of unique exposure to an environmental harm," says Christina A. Clarke, an epidemiologist at the Northern California Cancer Center and a leading expert on Marin's plight.

Clarke and other researchers say Marin's status may be largely explained by its attributes as one of the nation's smallest urban counties. Its 250,000 residents are predominantly white and well-off financially, characteristics long associated with higher rates of breast cancer. Cancer rates are reported for counties, but not for cities and towns. If they were, Clarke says, places such as Beverly Hills, Calif., or Chevy Chase might exhibit similarly high breast cancer rates.

Marin's status could potentially help women elsewhere if activists succeed in encouraging further local research, making the county, as Clarke hopes, "a petri dish" to study what it is about the life of a professional, well-off white woman that makes her so susceptible to breast cancer.

Evidence has been steadily accumulating to reinforce this connection. Results published last month of an ongoing study of 133,479 California teachers and administrators found a rate of invasive breast cancer that was 51 percent higher than that found in non-Hispanic white women of a similar age throughout the state.

Researchers offer several possible explanations. Educated, professional women, such as the teachers and a great portion of Marin's female residents, generally have better access to medical care, including screening for cancer; that leads to more diagnoses. Better medical care may also have included more combined hormone replacement therapy, only recently linked to increased breast cancer risk. Furthermore, in a family with two professional incomes -- especially common in Marin, where the average household income tops $80,000, almost $30,000 more than national average -- women often delay having children or do not have them at all. These characteristics have long been thought to increase the risk of breast cancer, the theory being that such women have more menstrual cycles at a younger age, exposing them to higher levels of estrogen, which can encourage tumor growth.

Beyond these issues, women here worry about a host of other possible dangers hidden in what looks like a fortunate lifestyle: the hectic schedule of two working spouses, pesticides on lawns, the chemicals in the plastic bottles of the ubiquitous designer water.

"I've always thought it was the stress," says Christine Schadlich, 42, a former real estate portfolio manager diagnosed with breast cancer three years ago, just after the birth of her second child. "It takes a lot of effort to maintain things here, with two parents working. My health was always on the margin."

Researchers have long known that chronic stress can harm people's immune systems. In recent years, several studies have indicated that a common way to cope -- by having a few drinks, as Schadlich says she often did -- is associated with higher rates of breast cancer, though the medical reasons for this remain unclear.

Schadlich says she quit drinking after her diagnosis. She also quit her job and says she is trying to simplify her life. Even so, she felt frustrated when her doctor, as she tells it, attributed her case to demographics.

The word raises the hackles of many women concerned about cancer, particularly those who feel it dismisses concerns about circumstantial evidence linking widely used chemicals, including some found in plastics and pesticides, to rising rates of breast cancer.

"It's easy for them to say 'demographics', but -- hello? There hasn't been enough research yet into what's in our air and in our soil and in the products we use," says Fern Orenstein, 44, a six-year cancer survivor and health education specialist. "Maybe what it is isn't unique to Marin, but maybe it is environmental, and we just have more of it here."

So many residents share these suspicions that on Nov. 9, 3,000 community volunteers for the Marin Cancer Project are planning to go door to door polling residents and asking for a $1 donation to map the incidence of all types of cancer. "The response has been like in the movie, 'Field of Dreams,' " says the group's director, Judi Shils. "If you build it, they will come."

Still, tracking potential environmental factors in breast cancer is extraordinarily difficult, experts say. The interaction between an individual's genes and exposure to potential toxins is complex, and is why some smokers get lung cancer, while other smokers do not.

In August, scientists involved in a study of reportedly high breast cancer rates in Long Island said they had found no links to pollution or other environmental factors. The research, supported by $30 million in federal funding, had focused on industrial chemicals, including two recognized "endocrine disruptors" -- substances that can affect hormonal systems. But the lack of conclusions hasn't ended suspicions.

"We know that lifetime exposure to estrogen is a risk factor," says Sheldon Krimsky, a Tufts University professor who studies environmental health hazards. "So it is logical that if we have chemicals that are creating more estrogen, the risk may go up." Such chemicals, says Krimsky, can be found in cosmetics, lawn care products, household cleansers and certain plastics, but research into their potentially harmful effects is moving "at a snail's pace."

The Marin Breast Cancer Watch, a group of survivors and other activists, has been fighting to focus attention on environmental exposure since 1997, when women began sticking pins on a map to see if the cancers were clustered.

Its members have supported five different small studies, funded by county, state and federal agencies, including a three-year project comparing the adolescent experiences of 300 Marin County breast cancer patients with those of 300 local women who do not have the disease.

One finding that may be illuminating is how long women say they have lived in the county. Clarke hypothesizes that the climb in the local breast cancer rate in the 1990s owes to departure of low-income women who could no longer afford to live there. The group took pride in a recent visit from Kenneth Olden, director of the National Institute of Environmental Health Sciences at the National Institutes of Health. "You've made your case that rates are higher here than anywhere else," he told them, "and you deserve our attention."

In an interview, however, Olden said he hadn't heard convincing evidence linking the high cancer rates to any particular environmental problem. "It looks like it's going to be demographics," he said.

As the search goes on for exactly what that means -- what special risks women here face -- Marin may have much to teach the country.

"There are lots of educated, affluent women scattered around the country," Clarke says. "For them, Marin women may be canaries in the coal mine."

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