The state of California wanted a more detailed geographic view of the problem. The non-profit group Public Health Institute out of Oakland was given a grant to identify, if any, these breast cancer clusters. What they found is now creating a lot more questions about risk factors.
Since 1994, researchers have tried to figure out why Marin County has high rates of breast cancer. They've come up with a list of risk factors. "Alcohol is associated with an increased risk of breast cancer. Clearly, taking hormone replacement therapy," Zero Breast Cancer Executive Director Janice Barlow says. Being white, having children late or not at all, are also risk factors.
But many women in Oakland, Berkeley and Richmond don't necessarily fall into some of those categories yet, those three cities in Alameda County are now said to have higher breast cancer rates than the state average. Researchers with the California Breast Cancer Mapping Project also found parts of Contra Costa, Napa, Sonoma, Solano, Santa Clara, and San Mateo Counties had 10 to 20 percent higher rates. The project relied on data form the California Cancer Registry and looked at cases from 2000 to 2008.
Zero Breast Cancer is an advocacy group in Marin County and its Executive Director, Janice Barlow, was involved in the project. She says it's unknown what is contributing to the higher rates, but says it could lead to further research. "If I was living in Berkeley, I would go talk to my supervisor and say, 'We're in your district. Your district is one of these areas that was identified. Why?" she told ABC7 News.
Marika Holmgren lives in Half Moon Bay which also made the list of those areas with higher rates. She was diagnosed with breast cancer six years ago. "When we start to gather this information and see that certain areas have elevated risks, it leads us to ask the question why and what can we be doing about it?" she said.
Having a lot of breast tissue is associated with higher risk of breast cancer. Dense breast tissue and a tumor appear white on a mammogram. So, doctors in California will have to notify women in writing if they have high breast density. This way, additional screening will be recommended. That law goes into effect April 1, 2013.