Within the scope of the project CARLOS (Cancer Registry Lower-Saxony), a software system — CARESS (CARLOS Epidemiological and Statistical Data Exploration System) — was developed to support modeling and conducting of descriptive epidemiologic studies. The fundamental idea was to implement a powerful core of a system for statistical analysis, which is easily extensible with regard to both data types and algorithms for processing the data. We followed a knowledge-based approach, i. e. a strict separation of data and knowledge on the one hand and the control cycle processing this knowledge on the other. The main concepts concerning data structures, methods, and data processing are presented. Special emphasis is put on the underlying data analysis model and the user interface, namely a visual workbench providing easy access to the whole trail of a study and all relevant data and knowledge. CARESS aims at novel techniques for analysing cancer clustering using advanced database technology to support multidimensional analysis.