Spatial Data Analysis Support for Cancer Epidemiology in CARESS

CARTools, a toolbox designed to support population-based cancer registries, is currently being developed at OFFIS, an institute for computer science. The first application area of this toolbox is the registry being established in Lower-Saxony, a federal state of Germany. CARLOS (Cancer Registry Lower-Saxony) is the name of the corresponding project, started in 1993. The CARTools comprise four tools, one of which is CARESS (CARLOS Epidemiological and Statistical Data Exploration System), implementing various routines for statistical and epidemiological data analysis on the registry database. In this paper, the functionality of CARESS with respect to supporting spatial data analysis – which is the main focus of this system – and the design of the integration of data analysis features in an interactive graphical user interface will be presented. The system is supposed to provide different features and interfaces for different user groups (epidemiologists, registry staff, external researchers) and different tasks (e.g. quality control, incidence monitoring, cluster analysis). To ensure both efficiency and flexibility, the underlying database system strives to integrate concepts from the fields of spatiotemporal, multidimensional and statistical database systems. 1 The Project CARLOS To reinforce efforts in the fight against cancer and to improve knowledge about potential causes and risk factors for cancer – aiming at an improved prevention –, the Ministry of Social Affairs forces the establishment of a homogeneous population-based cancer registry in Lower-Saxony, a federal state of Germany, since 1992. The name of the corresponding project, which started in 1993 with a pilot period, followed by a test period 1995-97, and which is presently beginning on routine data collection, is CARLOS (Cancer Registry Lower-Saxony) [AFH+96]. Evaluation of the applicability of a model for cancer registration proposed by Prof. Michaelis (Mainz) [MK92], also the Federal Cancer Registration Act passed in 1995 is based on, has been the main task in the pilot period. This model suggests a distinction between two separate offices: A notification office („Vertrauensstelle“) collects and encrypts patient-related reports, before transferring them to the registration office („Registerstelle“), which persistently stores, links together, and analyses the data. Concepts for data encryption and record-linkage have been designed, evaluated, and standardised [AMIT96]. Apart from OFFIS, which will take over the part of the registration office, the main collaborating partners in the project are – under the management of the ministry – the Association of Panel Doctors in Lower-Saxony („Kassenärztliche Vereinigung Niedersachsen (KVN)“) and a number of additional cancerregistering institutions, like clinical registries, pathological laboratories, etc. The KVN is expected to contribute the largest amount of reports to the registry by way of the „Nachsorgeleitstellen“, which are institutions engaged in patient follow-up and organisation of secondary therapy and further examinations. Currently, the project is in the final stage of a test period lasting from 1995 to 1997. During this time, special emphasis has been and is put on the integration of a variety of cancer-registering institutions, the implementation of routine registration, and computer-based support for epidemiological data analysis. To provide software support for almost all steps of population-based cancer registration, especially in Lower-Saxony, a toolbox called CARTools is being developed at OFFIS [AFH+96]. The CARTools comprise four tools providing support for the main tasks „data transfer to the registry“, „encryption of data sets“, „record linkage“ and „data analysis“. CARESS (CARLOS Epidemiological and Statistical Data Exploration System) is the name of the tool implementing the statistical and epidemiological data analysis process based on the registry database. 2 Analysing the Registry Database with CARESS Experiences in a number of cancer registries have shown that there is still a lack of facilities to analyse the large amounts of collected data flexibly and efficiently both for routine monitoring and reporting and to answer public ad-hoc queries regarding supposed clusters of cases or increased incidence rates. Often, data storage and management, statistical analysis and visualisation of results are implemented by different systems and tools, so that data transfer and conversion takes a lot of time or is at least inconvenient. Furthermore, in many cases new problems and queries with just some parameters changed afford new software routines to be written and integrated. The data analysis system CARESS is designed to meet these needs and to make work at population-based cancer registries more efficient and flexible. It is supposed to provide a comfortable data analysis environment for different groups of users (cf. fig. 1) interested in • quality control, i.e. calculation of indices like HV (proportion of histologically verified tumours), M/I (relation of mortality to incidence), DCO (number of cases only known by means of a death certificate), etc., • incidence monitoring, survival analysis, and cluster analysis, • formation of hypotheses concerning potential cancer risks by comparison with background information, • generation of reports and data export.