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Last Edited: 5/11/2005

Regional Variations in Breast Cancer Rates in California
09/1999 - 08/2004


Geographic location is among the greatest predictors of breast cancer incidence, with more than a ten-fold difference among regions of the world.  Observed regional variations in breast cancer incidence have been a source of public health concern in California and have generated many hypotheses regarding the disease's etiology.  California has some of the highest rates of breast cancer rates worldwide; there also exist substantial variations in rates within the state.  Because incidence rates typically are higher in more urbanized areas some have speculated that environmental exposures may be driving these higher rates.

This study aims to examine factors underpinning geographic patterns of breast cancer incidence in California.  The analyses are performed at both the ecologic level, using statewide cancer incidence data, as well as in a cohort analyses within the California Teachers Study (CTS).  Included in these analyses are evaluations of:

  • The degree to which neighborhood socioeconomic status and urbanization explain regional differences in breast cancer rates.
  • The degree to which established beast cancer risk factors explain regional differences in breast cancer rates within the California Teachers Study cohort.
  • Residential proximity to agricultural pesticides and breast cancer incidence.
  • Traffic related emissions and breast cancer incidence.
  • Hazardous Air Pollutants and breast cancer indicence.
  • Biomarkers of exposure to traffic-related emissions and agricultural pesticide use as they may related to urban/rural differences in cancer incidence.

Living in an area with high breast cancer rates often creates undue anxiety among residents.  Elucidating the factors that explain the excess breast cancer in these areas offers the opportunity to both quell public concern and further the understanding of breast cancer etiology.