| Objective By collecting the incidence data of esophageal cancer, gastric cancer,colorectal cancer and liver cancer and demographic data of villages and towns as the units,we described the epidemic law of the main digestive tract cancer and tried to explore the distribution and aggregation of villages and towns as the dimension of space, providing evidence for the causal inference, conducting early screening and formulating prevention and control strategies of digestive tract cancer. Methods We chose three cancer registries,Changle City, Fuqing City and Hanjiang District of Fujian Province to launch this study. We used the four main digestive tract cancer incidence data and demographic data, coming from Changle cancer registry from 2007 to 2011, Hanjiang cancer registry and Fuqing cancer registry from 2010 to 2012 to calculate crude incidence of villages and towns respectively and establish geographic database. We applied the technology of GIS,spatial analysis and epidemiological method with ArcGIS software to import polygon data of each village, in order to analyze the incidence of digestive tract cancer with the global and local Moran’s I and G statistics spatial auto-correlation analysis. We used SaTScan software to take space scan on the number of the digestive tract cancer cases to identify risk areas. Results The general epidemic features of the main digestive tract cancer in Changle City were a high incidence of gastric cancer and a low incidence of esophageal cancer; in HanJiang District, the epidemic features were a high incidence of gastric cancer significantly; in Fuqing City, the digestive tract cancer were given priority to gastric cancer and liver cancer, but either of them wasn’t on a high level. In the study area, global Moran’s I index of esophageal cancer, gastric cancer, colorectal cancer and liver cancer were0.734011, 0.932897, 0.633696, 0.644418 respectively, P<0.01. The G statistics value of esophageal cancer, gastric cancer, colorectal cancer were above zero respectively, P< 0.01.By the local Moran’s I, we found that esophageal cancer, gastric cancer, colorectal cancer and liver cancer had HH area(high- value gathered area), HL area(high-low concentrated areas), LH area(low-high value gathered area) and LL area(low-low concentrated areas)on the scale of the villages and towns. The result of local G statistics index auto-correlation analysis showed that four kinds of cancer had different hot and cold spots. Four types ofcancer in the three research cities(districts) had been scanned with risk gathered areas.Conclusions The incidence of esophageal cancer, gastric cancer, colorectal cancer showed a certain spatial clustered distribution in the study area in Changle City, HanJiang District,Fuqing City.Spatial auto-correlation analysis and spatial scanning analysis based on GIS using for the cancer incidence of the main digestive tract cancer were more intuitive, clearer,and more accurate to reflect the incidence of geographical spatial distribution and accumulation characteristics of the main digestive tract cancer of the three areas than traditional descriptive epidemiology method which was based on the frequency tables. In the study of spatial epidemiology, it is necessary to use this two different spatial analysis method, Moran and G statistics spatial auto-correlation and SaTScan space scan, flexibly,and integrate and compare with each other. Then, getting spatial distribution of information into the scene, which will explain the results from the spatial distribution, may guide the practical prevention and control work from the spatial description to causal inference. |
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