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Progress in Addressing Breast Cancer Rates in Marin County

  • Posted: March 28, 2003

A transagency task force is making steady progress on the proposed plan to address breast cancer rates in Marin County, Calif., and other counties in the United States. The plan, first unveiled on Nov. 21, 2002, by National Cancer Institute (NCI) Director Andrew von Eschenbach in a meeting with Representative Lynn Woolsey, proposed to determine actual breast cancer rates in Marin and other counties, define the role of known risk factors, and define the role of environmental factors in breast cancer risk.

The task force consists of representatives from the U.S. Department of Health and Human Services, including NCI, the National Institute of Environmental Health Sciences (NIEHS) and the Centers for Disease Control and Prevention (CDC), and the Environmental Protection Agency (EPA). To date, progress has been made in the following areas:

  • Determining actual breast cancer rates in Marin and other counties

The estimates of breast cancer incidence (number of new cancers per year) most recently reported for Marin and other areas of the country were based on 1990 census information. Data from Census 2000 have enabled researchers to recalculate rates for Marin. Preliminary results show that revised incidence rates for Marin County based on the 2000 census are substantially lower than the rates calculated using 1990 census information. The discrepancy between using the 1990 and 2000 census data is due to projected population growth differing considerably from actual population growth. Comparisons of recalculated rates to other parts of California and the country are in progress.

In addition to the calculation of cancer rates using current census figures, NCI and NIEHS already have committed $1.9 million over a three-year period to the study of Geographic Information Systems (GIS) in Northern California. The two institutes continue to work with GIS experts to discuss ways to enhance the systems to address geographic differences in breast cancer occurrence. GIS is a research tool that can correlate information from multiple sources, including demographic, environmental, and epidemiologic databases, in order to study causes of disease in geographic areas.

  • Defining the role of known risk factors

With encouragement from NCI, the Northern California Cancer Center in Union City, Calif., submitted an application for funding to examine the prevalence of established breast cancer risk factors such as late childbearing and other reproductive events, personal history of breast cancer, and hormone replacement therapy. This proposal was submitted via NCI's Rapid Response Surveillance Studies (RRSS) mechanism, which allows researchers to conduct innovative population-based surveillance and outcome studies on scientific inquiries deemed to be of high priority to NCI, Congress, and advocacy groups.

Also via NCI's RRSS mechanism, investigators at the Northern California Cancer Center proposed to develop statistical models to predict attributable risk (the amount of disease that could be due to specific risk factors) based on the breast cancer risk factors of alcohol use, hormone replacement therapy, and breastfeeding. The results of this analysis can be used to measure the benefits of interventions that were designed to modify these risk factors.

  • Defining the role of environmental factors

At the November meeting, Dr. von Eschenbach encouraged Bay Area investigators to submit a proposal for funding as a Breast Cancer and the Environment Research Center. Breast Cancer and the Environment Research Centers, jointly funded by NIEHS and NCI, are a network of centers in which multidisciplinary teams of scientists, clinicians, epidemiologists, breast cancer advocates, and others work collaboratively on scientific questions that focus on how chemical, physical, biological, and social factors in the environment work alone or in combination with genetic factors to cause breast cancer.

In February, NCI convened a meeting with representatives from NIEHS, CDC, and EPA to develop guiding principles for addressing high cancer incidences throughout the country, including Marin County. This is one in a series of meetings focused on a science-based approach for assessing the contribution of environmental exposure to breast cancer risk. The task force is assessing available technologies and processes that may be valuable in answering questions about the impact of the environment on breast cancer risk and discussing how better approaches might be developed.

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For more information about cancer, visit the NCI Web site at or call NCI's Cancer Information Service at 1-800-4-CANCER (1-800-422-6237).

Resource List

1.  Request for Applications - Breast Cancer and the Environment Research Centers

2.  National Toxicology Program, National Institute of Environmental Health Sciences

3.  Publication - United States Cancer Statistics: 1999 Incidence - released Nov. 18, 2002