This flowchart outlines, in four steps, the process followed when a suspected cluster of non-infectious diseases (cancers, degenerative diseases, chronic inflammatory diseases, congenital malformations, etc.) is reported to public health agencies: 1) Handling of the report; 2) Analysis of the spatiotemporal cluster; 3) Assessment of the relevance and feasibility of a specific epidemiological study to identify the factors contributing to the cluster; 4) Organization and planning of the specific epidemiological study.