Geographical information systems (GIS) have been extensively used to research public health issues in recent years. Cancer is one of the most important health issues around the world. In this study, a standard, effective and efficient GIS-based decision support system is established to ensure taking necessary measures for cancer cases, providing assistance to reveal the relationship between environmental health and geograph- ical location, which may lead to cancer, keeping cancer cases under control, and places being recorded where the patients diagnosed with cancer dwell, together with their geographical locations. This system was fulfilled in the city of Sivas (Turkey).
As a result of investigating, the cancer cases occurred between 2007 and 2010, The average of the can- cer incidence rates for these years were calculated for both males and females and the curve equations repre- senting them were estimated with a high coefficient of determination (R² =0.99). Whereas the coefficient of determination (R²) that expresses the strength of the relationship between the variables in the equation is 0.991 for females, this coefficient for males is 0.998. These equations almost represent existing data used to calcu- late the cancer incidence rates of the standardized age groups of males and females between 2007 and 2010.