Abstract
Objective: The purpose of this study was to examine the effects of the interoperability of breast cancer screening facilities located in different local governmental jurisdictions. Methods: The 53 regions in Tokyo, with exception of the islands, were included in this study. Demographic data on women over the age of 40 years living in each city block on January 1, 2009, were derived from the Basic Resident Register, which also provided the name and address of the facilities at which screening for breast cancer were conducted in 2009. We measure three primary dependent variables: 1) the distance from residence to the nearest screening facility, 2) differences in the distance to the screening facility among subjects, and 3) the geographic distribution of subjects. We defined the point of residence as centroid of each city block, and the distance from each participant's residence to the nearest cancer screening facility was defined as the linear distance from the relevant centroid to the nearest screening facility. The Gini coefficient of the distances from residences to facilities was used as the criterion for evaluations of the degree to which such distances were equal for subjects. The Gini coefficient and the standard deviation of the number of subjects nearest to the screening facility were used to measure the geographical unevenness of the distribution of subjects. The results revealed two patterns: 1) subjects who received breast cancer screening at the facility specified by their local government (pattern A), and 2) subjects who received interoperable breast cancer screening services at the nearest facility, which was located within the jurisdiction of another local government (pattern B). We analyzed the differences between these two patterns in terms of the three primary dependent variables using geographic information system (GIS) software ArcGIS version 9.3 (ESRI Inc., Redlands, CA). Results and Discussion: Nearly one-quarter of the subjects (24.2%) lived farther from their local screening facility (2,908 m, pattern A) than from a facility in another jurisdiction (1,640.5 m, pattern B). Thus, the average distance to the nearest facility was reduced by 307.4 m per person when calculations were not confined by jurisdictional boundaries. The Gini coefficient indicated that the equality of the distance was 0.383 among subjects following pattern A and 0.363 among those following pattern B. No statistically significant differences were observed in Gini coefficient or standard deviation. Conclusion: When residents of Tokyo (excluding the islands) receive interoperable screening services for breast cancer at the nearest facility, irrespective of jurisdictional boundaries, the distance from residences to screening facilities may be reduced, and the inequality in the distance to these facilities from subject's residences dose not increase.
