<p>The biggest difference between Marin County women with breast cancer and their neighbors without the disease is the amount of alcohol they consume - - with the heaviest drinkers raising their risk almost fourfold, researchers report.</p>
<p>In the first study comparing a group of women in Marin County with breast cancer to a control group, researchers at UCSF found that the length of time spent living in that county had no bearing on their likelihood of developing the disease. That suggests that a mysterious toxin in the air, water or soil in Marin County is not a likely cause for the area's high breast cancer rate, according to Margaret Wrensch, professor of epidemiology at UCSF and lead author of the study posted online last week in the journal Breast Cancer Research.</p>