Investigating Geographic Distribution of Colorectal Cancer Cases: An Example from Penang State, Malaysia

The map has widely been used to depict and disseminate information on the spatial distribution of various diseases, including cancer cases. Increasingly, population-based cancer data need to incorporate spatial information that enables various spatial and proximity analyses to be conducted whereby results can be graphically presented. Yet, disease maps as a communication form remain largely unexamined. This is probably due to the confidentiality of the disease cases and the cost of incorporating the spatial component in the database. In the state of Penang, Malaysia, although Penang Cancer Registry (PCR) collects and collates data of all cancer cases diagnosed in the state as well as cancer cases diagnosed elsewhere whose home address is given as a Penang address, geographical location is not included. Mapping of cases using information from PCR will give a fairly complete picture of spatial distribution of cancer cases from Penang State and clustering of cases can be readily evaluated. This study demonstrates the application of spatial analysis methods and GIS in mapping and understanding the spatial distribution of Colorectal cancer cases in Penang State. The cases were mapped to identify spatial clustering of cancer cases and measure distance from existing health facilities. This study finds that spatial information is pertinent to be included as part of the database kept by Cancer Registry since this information can effectively be used for communications with and education of the public, as well as for planning health care delivery.