The National Enhanced Cancer Surveillance System: A case-control approach to environment-related cancer surveillance in Canada

This paper describes the rationale and basic design of the National Enhanced Cancer Surveillance System. The system is designed to facilitate timely, systematic evaluation of environment-cancer concerns and strengthen cancer surveillance in Canada. There are three key activities: (1) National community-level environmental quality database: The database, created by Health Canada, includes systematic, easily accessible, community-level information on air and water quality. Information includes a national inventory of municipal waste disposal sites, municipal drinking water data, air quality data, historic industrial location and productivity data. (2) Case-control surveillance: The Provincial Cancer Registries are collecting individual data from a large, Canada-wide, population-based series of newly-diagnosed cancer cases for 18 types of cancer and a population control group. Mailed questionnaires and telephone followup are used to gather data on residential and occupational histories, diet, physical activity and other risk factors for cancer. Data for over 20,000 cancer cases and 5000 controls have been assembled between 1994 and 1997. The cancer and population control data are being linked to the environmental database to facilitate systematic, community level, case-control assessment of cancer risk related to air and water quality. (3) Geographic surveillance network: Areas of high and/or unusual patterns of cancer incidence are being examined through temporal and spatial mapping, cluster analysis and risk factor evaluation. (C) 1998 John Wiley & Sons, Ltd.