Breast cancer occurrence in Marin County: Why is it higher than average?
Data from our cancer registry show that breast cancer occurrence (rate) in Marin County is higher than in other counties, and many people there are concerned that the higher rate might be related to something in the environment. However, we also know that women with certain characteristics are at higher risk of developing breast cancer than others. Women who are affluent, well educated, and have few children have a greater chance of developing breast cancer than women who do not have these characteristics.
This study looked to see if these types of women were more likely to live in Marin County, and if that explained why there is a higher occurrence of breast cancer in Marin. Looking at information for the years 1988-1992, we found that women who had these breast cancer risk factors were, in fact, more likely to live in Marin County. We looked at other areas around California that also had a large number of higher-risk women living there, and found that breast cancer occurrence in those areas was also higher than average. The results of this study suggest that breast cancer occurrence is higher wherever there are more high-risk women, such as in Marin County, and that there was no reason to believe that the environment in Marin was causing the higher rate of breast cancer.
NCCC Principal Investigator: Angela Witt Prehn, Ph.D.
Collaborator: Dee W. West, Ph.D. (NCCC)
Funding Source: Surveillance, Epidemiology, and End Results (SEER) Program
Publications:
Prehn A, Clarke C, Topol B, Glaser S, West D. Increase in breast cancer incidence in middle-aged women during the 1990s. Ann Epidemiol 2002 Oct; 12(7):476-81.
Prehn AW, West DW. Evaluating local differences in breast cancer incidence rates: A census-based methodology. Cancer Causes and Control 1998;9:511-517.
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