County Faces Highest Breast Cancer Rate

Aug. 4, 2002 -- Marin County, Calif., just across the bay from San Francisco, is considered an extremely desirable place to live.

It boasts pristine woodlands, beautiful waterways and, with Mount Tamalpais as a stunning backdrop, some very pricey real estate.

Marin's population is predominantly white, affluent, highly educated and very health-conscious.

"I try to eat organic foods as much as I can," said Lynn Oberlander, a local resident. "I try to get my stress level down. I go to yoga. And I hike and I exercise."

But despite all the advantages, Marin County has the highest rate of breast cancer in America, possibly even in the world.

"They tend to be about 40 percent higher than the national average and about 30 percent higher than the rest of the Bay Area," said Tina Clarke, an epidemiologist with the Northern California Cancer Center, who has been studying breast cancer in Marin County since the mid-1990s.

Contact With Cancer

Almost every woman living there has seen it.

"You know, you can't be a middle-aged woman in Marin County and not be aware of the fact that the incidence of breast cancer is much higher here than elsewhere in the United States," said Kim Wright-Violic, a Marin County resident. "In a community that's this small, inevitably you know somebody who either has had cancer and is in remission or has died of cancer."

Among white women aged 45 to 64, the breast cancer rate in Marin has increased 72 percent in the last decade. One year was especially alarming.

"Between 1998 and 1999, there was a 20 percent increase in breast cancer in white, non-Hispanic women living in Marin County," said Janice Barlow, executive director of Marin Breast Cancer Watch, a grass-roots organization formed by alarmed residents in 1995 to study the problem. "It's huge."

For the most recent year for which data is available, 1999, a total of 285 women in Marin County were diagnosed with invasive breast cancer. A total of 53 died.

High-Risk Portrait

At the Marin Breast Cancer Watch, Clarke has compiled a portrait of the high-risk group, using census data and cancer registry information.

"Together that gives us a profile of women who are, you know, socioeconomically privileged, tend to be very well-educated, affluent, thereby kind of tend to be professional," Clarke said. "With the professional comes having fewer children or not having children at all, delaying child bearing all together.

Dr. Georgie Farren fits that profile. Ten years ago, at the age 42, with three very young daughters to care for, she was diagnosed with breast cancer.

"It was definitely a shock," she said. "I was at the time a runner and reasonably healthy, careful of what I did and what I ate."

Farren is involved in a study on whether risk factors from adolescence might contribute to the high rate.

"Two of those women have died of breast cancer since we began it," she said. "So, you know, it's a disease that's serious and it's taking its toll on the population."

Could the fact that educated, affluent women tend to get regular mammograms account for the high numbers being reported? Clarke says no.

"If everyone was just getting a lot of mammography and they were catching it earlier, I think you would expect that the Marin women would have less of the late-stage disease, but they have about the same proportion of the late-stage disease," she said. "And they have a much higher mortality rate, just like their incidence rates."

That high breast cancer rate is evident to oncologists in local hospitals.

"I noticed the breast cancer rates were high, and almost immediately my entire practice filled up with women with breast cancer, " said Dr. Francine Halliberg, who started practicing in Marin County 14 years ago. "And every year, I see more women with breast cancer."

A Demographic Issue?

One of those women is Christine Chadlick. She is a business professional who had her children in her 30s, which is considered late in reproductive terms. Delayed childbirth is considered a risk factor.

"I fit the demographic profile perfectly," she said. "So if it is a demographic issue, then I'm sitting right in the middle of that. Not much I can do."

But what does that mean a demographic issue? Does that mean the high incidents of breast cancer is linked to being affluent and educated?

"It obviously isn't a risk factor," said Barlow of Marin Breast Cancer Watch. "It just is a characteristic. There must be some behaviors that go along with being high socioeconomic level.

"What are those behaviors?" she added. "Well, I think those are the things that we're trying to study. … That's the mystery."

Cause Speculation

The Marin volunteers include Chadlick, whose cancer was caught early. She is now part of a study looking at whether the cancer cases might be clustered within certain areas of the county.

"They had us map our neighborhood," Chadlick said. "There is a creek in my neighborhood. We're near the ocean, obviously. There is a Styrofoam cup plant."

At this point, the only thing they know for certain is that they have a huge problem. As for what's causing it, there are few facts and a ton of theories.

"Maybe something in the ground?" Oberlander said. "Maybe something in the water? Maybe something in the air? Maybe it's all of the satellite antennas? I don't know."

One theory is that these women would get breast cancer wherever they lived, but because so many who are white, affluent and educated live in Marin, so the area shows up as a statistical phenomenon.

"I think of it as almost a petri dish," Clarke said. "It happens to be a county. It happens to be pretty small. It happens to be homogeneous."

Risk Factors

Clarke's approach is strictly scientific. The epidemiologist looks first at known risk factors: "Having no children at all, or having few numbers of children, having higher levels of education and income — those are the ones we've really focused on."

Another risk factor: Affluent women tend to get better medical care and may be exposed to more radiation over the years. They also tend to use hormone replacement therapy during menopause, and estrogen levels may play a role. And there are other habits associated with this demographic group.

"I wonder a little bit about alcohol," Clarke said. "Alcohol consumption is a risk factor for breast cancer, and we've seen in some previous studies conducted in the entire Bay Area that women out here tend to drink more."

The fact that so many women here fall into the same high-risk group may not entirely explain the high rate of breast cancer.

Many residents and some researchers wonder if there is something in the environment, and almost everyone has a theory. Some point to the manicured lawns and the use of pesticides. Others wonder if it might be the chemicals used by dry cleaners. Affluent people tend to use dry cleaners more often than others.

The environmental theories have prompted many residents of Marin to take extra precautions — buying nonpolluting household cleaning products, for example, and being careful not to dump potential toxins down the drain.

"I'm assuming it's got to be some kind of environmental aspect," Wright-Violic said. "I do not buy the idea that it has to do with affluence or education or early detection because there's too many other affluent communities that don't match the cancer rates here."

No other community matches the rates of Marin, but a couple of studies of similar communities suggest that the lifestyle choices of the affluent may be a contributing factor.

A study done in Newton, Mass., for example, pointed to the higher use of pesticides in affluent homes, saying these finding are "intriguing because components of many pesticides contain endocrine-disrupting compounds." Exposure to those compounds may increase the risk of cancer.

Seeking Answers

The community activist group in Marin, meanwhile, is trying to raise funding for more scientific studies that might solve the mystery.

"I think it's the possibility of being able to prevent breast cancer is really what makes us get up early and go to bed late," Barlow said.

The answer can't come too soon for women like Chadlick. She is recovering from her breast cancer, but she's already taken some preventive measures of her own.

"A lot of us are trying to reduce the stress in our lives," she said, "even though there is no proof" stress is a factor.

Barbara Niehe, who has lived in Marin for 25 years, is battling another round of cancer. Prevention is moot for her, but she would still like some answers.

"I think I had my eyes and ears closed for some many years because it wouldn't happen to me, it couldn't happen to me," Niehe said. "And I was healthy. I was an outdoor person. I hiked five miles a day. I didn't smoke. I drank a little. So I wasn't concerned."

Now, thanks to the efforts of the Marin Breast Cancer Watch, the whole community is concerned.

"I just can't help but wonder if this is, you know, the canary in the gold mine," Clarke said. "And this could be happening in smaller communities that are, you know, swallowed up in big counties and we'll never be able to do good cancer surveillance on a yearly basis there … the way we can in Marin."