Methodological Issues - Geographic Information Systems

Geographic Information Systems (GIS) identify and display geographic patterns, which are particularly useful in examining cancer screening, incidence, and mortality rates in the U.S. Additionally, these methods can be used to investigate any number of geospatially-related questions. For example, researchers can use GIS to investigate the distances between patients and screening or treatment facilities so as to determine why individuals in certain geographic regions have different rates of screening or therapies. Changes over time can also be investigated. GIS systems can aid in the communication of information to the public and public health professionals. The goal of GIS research is to improve the methodology and adapt it to the monitoring, detecting, and communicating trends.

Additional information on GIS can be found at: http://surveillance.cancer.gov/research/gis

RRSS investigators are conducting studies to:

• develop population estimates on a very small grid to compute and compare different geographic measures of cancer;
• develop and apply new methods for smoothing temporal-spatial trends in cancer incidence;
• determine the usefulness and feasibility of using GIS for reporting cancer incidence on the Internet;
• evaluate GIS capabilities and test various ways in which geographically based cancer incidence reporting systems can be used;
• assess the accuracy of geocoding of cancer registry data;
• evaluate the use of state motor vehicle records to improve the accuracy of geocoding patients' addresses at time of diagnosis
• use GIS technology to investigate the relationship of non-melanoma skin cancer to area-based indirect measures of UVB radiation in New Mexico

Registries Funded to Conduct these Studies

Connecticut
Detroit (Metropolitan)
Iowa
New Mexico

Key Findings

Researchers geocoded the addresses of non-melanoma skin cancer patients and calculated an ambient UVB measure for each town or city. The UVB measure and the rate of non-melanoma skin cancer were positively related.

The presentation of registry data in a GIS over the Internet was determined to be feasible and because the data would be presented in summary form, confidentiality problems would be unlikely.

Future Use

The use of GIS continues to gain popularity. Data that take advantage of geocoding are increasingly being made available on the SEER website. Additional research continues into the best methods for graphically presenting GIS data.