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"Bay Area breast cancer clusters seen; Marin not only spot in area with higher rate of disease"
2012-11-27 by Victoria Colliver from "San Francisco Chronicle" [http://www.sfgate.com/health/article/Bay-Area-breast-cancer-clusters-seen-4068698.php]:
California Breast Cancer Mapping Project
To read the report, go here: [www.californiabreastcancermapping.org]
Breast cancer clusters in California may not be limited to Marin County.
New research released Tuesday identified four areas of the state that have rates of the disease 10 to 20 percent higher than the state average.
Relying on U.S. census tracts rather than county-level data, researchers for the Public Health Institute's California Breast Cancer Mapping Project in Oakland were able to identify northern and southern Bay Area counties as "areas of concern." The two other areas were located in Southern California.
In the North Bay, higher rates of breast cancer were detected in Marin County, which is already well known for its disproportionately high rates of the disease, as well as contiguous portions of Sonoma, Napa, Solano and Contra Costa counties. The South Bay sections included parts of San Mateo County, northern Santa Clara County and southern Alameda County.
An important tool -
The project didn't attempt to identify reasons for the high rates in those areas, but the study is an important tool for further research, said Janice Barlow, executive director of Zero Breast Cancer, a nonprofit advocacy group based in Marin County. She served on the project's advisory group.
"This opens up whole new areas to look at and explore," Barlow said. "It's an opportunity to advance our understanding of why there are such geographic variations in breast cancer incidence."
About 26,300 new cases of breast cancer are diagnosed in women in California each year, leading to about 4,175 deaths annually.
Marin County has long been studied for its high rates of breast cancer, but many questions remain unanswered. Risk factors for the disease include having a family history of breast cancer, being white, hormone use after menopause, being an older mother or never having children, alcohol consumption, and having higher socioeconomic status. Still, many health experts say those factors don't explain the rate disparities along geographic lines.
"We can say definitively that breast cancer is caused by a combination of genetics, behavioral risk factors and the environment," said Dr. Eric Roberts, a research scientist at Public Health Institute and principal investigator of the California Breast Cancer Mapping Project. "The state of the science is that we really don't know what the mix is."
While the new study doesn't delve into the reasons behind the clusters, it offers a more specific geographic picture of the problem. Its authors suggest the results may be used by lawmakers and local health officials to redirect education, outreach and screening efforts.
U.S. census tracts -
The project relied on data from the California Cancer Registry involving all invasive breast cancer diagnoses from 2000 to 2008. It used U.S. census tracts, which meant the research differed from past efforts in that areas of study were smaller and often overlapped into adjacent counties.
In many cases, areas where higher breast cancer rates were noted shared some demographic similarities - for example, having a higher percentage of white women - than the state average, Roberts said. He dismissed the notion that greater access to health care leading to more diagnoses played a role, because the data included cancers detected after death.
In each of the four areas of concern, the rates of breast cancer varied from year to year, but remained well above the state average throughout the eight study years. For example, in 2008, the most recent year studied, the age-adjusted rate for women in the North Bay region was 17 percent higher than the state average. In the South Bay region, that figure exceeded 29 percent.
Roberts noted that the research is limited to where the women lived at the time of their diagnosis and did not include where they grew up and may have been exposed to elements earlier in life that contributed to their disease.
Breast cancer patient -
Marika Holmgren, 43, of Half Moon Bay was raised in an area outside Boston known to have relatively high rates of breast cancer. Diagnosed in 2007 with breast cancer at the age of 37, Holmgren learned from the study she lives in one of the newly identified regions with rates higher than the state average.
She said the mapping project offers important information.
"Looking into the causes is a really important factor in the cancer equation," Holmgren said. "A lot of time is spent on awareness and on cures, but not enough time is being spent on prevention and the reasons behind it all."