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Colorectal Cancer Incidence and Late Stage Maps of Iowa

Each pair of maps that follow illustrates how different spatial units can convey different spatial patterns even when they are constructed from the same data source. The first map of each pair aggregates Iowa cancer registry data by county of residence and directly maps the ratio of age-adjusted number of cancers for the county / age-adjusted expected number of incidences in the county. The second map of each pair—the spatially smoothed map—aggregates Iowa cancer registry data by groups of ZIPcodes that together have at least 50 age-adjusted expected number of cancer incidences and maps the same ratio as defined above. These groups are defined as the closest ZIPcodes from each point on a three mile grid that meet the at-least 50 expected cancer cases limit.

For the late-stage map pair, the same method is used as above and the ratios mapped are the observed late-stage incidences / all stage incidences.

The smoothed maps give more geographic detail and a more reliable measure of cancer rates than the county maps because they use measures of the rates for approximately 2000 different areas—compared with 99 separate county rates and they use approximately the same number of expected cancer cases in each measure—compared with vastly different numbers of expected cases in the counties. The authors of these maps believe that smoothed maps constructed in this way are superior for the purpose of cancer control and prevention activities especially when used at local levels. Colorectal Cancer Incidence Rates by County Map Image

Click map to go to the Welcome to the Iowa Consortium for Comprehensive Cancer Control Cancer Maps Site

Colorectal Cancer Smoothed Incidence Rates Map Image

Click map to go to the Welcome to the Iowa Consortium for Comprehensive Cancer Control Cancer Maps Site

Colorectal Cancer Late Stage Rates by County Map Image

Click map to go to the Welcome to the Iowa Consortium for Comprehensive Cancer Control Cancer Maps Site

Colorectal Cancer Smoothed Late Stage Rates Map Image

Click map to go to the Welcome to the Iowa Consortium for Comprehensive Cancer Control Cancer Maps Site

Organizations: The Department of Geography, The University of Iowa, made the maps under contract to the Comprehensive Cancer Control Program, Iowa Department of Public Health.

Contact Information:
1. Gerard Rushton, Department of Geography, 316 J.H.,
The University of Iowa, Iowa City, IA 52242. (319-335-0162); Gerard-rushton@uiowa.edu

2. Holly Smith, Program Coordinator, Comprehensive Cancer Control Program, Iowa Department of Public Health, Lucas State Office Building, 321 East 12th Street,
Des Moines, IA 50319, 515.281.0925, fax.515.281.6475, hsmith@idph.state.ia.us

Web address: www.uiowa.edu/~gishlth/ICCCCMaps

 

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Page last modified: November 15, 2006