Status Report

National Enhanced Cancer Surveillance System:
A Federal-Provincial Collaboration to Examine Environmental Cancer Risks

Kenneth C Johnson

The Laboratory Centre for Disease Control at Health Canada is the steward of the National Enhanced Cancer Surveillance System. The system was developed in the mid-1990s through a successful federal-provincial collaboration between the Environmental Risk Assessment and Case Surveillance Division (Cancer Bureau) and the provincial cancer registries.^a

The central component of the National Enhanced Cancer Surveillance System was built by collecting detailed, risk factor questionnaire information from a Canada-wide sample of 20,755 recently diagnosed patients with cancer (18 types) and 5,039 population controls. The data set includes over 1,000 cases of 11 major types of cancer in Canada and up to 700 cases of some rarer forms of cancer. In parallel, the Environmental Quality Database was developed to facilitate examination of the relationships between cancer and the quality of air and water in Canada. Geographic evaluation of national cancer incidence data (e.g. assessments of cancer cluster findings) and a communication component complete the system.

Data collected under the National Enhanced Cancer Surveillance System serve the national public health interest and disease surveillance by facilitating analyses to improve our knowledge of the role of environmental factors as influences on cancer in Canada. These data also allow the study of behavioural risk factors.

The National Enhanced Cancer Surveillance system can facilitate quick, yet thorough, analyses of cancer-environment issues that are important to the Laboratory Centre for Disease Control in its role as a key player in disease surveillance. A wide variety of analyses are now underway both federally and provincially. Below are two examples of analyses of considerable importance at Health Canada.

Passive and Active Smoking and Breast Cancer

Of particular interest are the provocative results described in the recently published article "Passive and Active Smoking and Breast Cancer in Canada, 1994-97" (see below). The article contributes to the emerging evidence suggesting a link between second-hand tobacco smoke and breast cancer. If the relationships suggested by this analysis and six other related published studies are confirmed, environmental tobacco smoke could prove an important breast cancer risk factor.

Chlorination of Drinking Water and Cancer Risk Assessment

Analyses are also underway to examine the association between chlorination disinfection by-products (CDBPs) in drinking water and bladder cancer, to support the current Health Canada (Health Protection Branch) initiative to re-evaluate national drinking water guidelines for CDBPs. This will be the first instance of a thorough analytic epidemiologic study being undertaken to examine the relationship between CDBPs and cancer in Canada, for locations outside of the province of Ontario. Additionally, by linkage to sophisticated water sampling analyses done by Health Canada's Environmental Health Directorate, the system can produce epidemiologic analyses of specific CDBPs that have never been evaluated in this detail. Finally, the system allows for detailed study of more than a dozen other cancers and CDBPs, many of which have never been examined in depth anywhere in the world.

Collaborative Research Opportunities

If you are interested in receiving more information on the data access policy and procedures or would like to discuss possible analyses using data from the National Enhanced Cancer Surveillance System data, please contact Ken Johnson (see Author References).

Selected Recently Published Journal Articles

Johnson KC, Mao Y, Argo J, Dubois S, Semenciw R, Lava J. The National Enhanced Cancer Surveillance System: a case-control approach to environment- related cancer surveillance in Canada. Environmetrics 1998;9:495-504.

Mao Y, MacNeill IB, eds. Proceedings of the Workshop on Retrospective Exposure Assessment Using Emission Inventories. Environmetrics 1998;9(5):493-598.

Villeneuve PJ, Johnson KC, Kreiger N, Mao Y, and the Canadian Cancer Registries Epidemiology Research Group. Risk factors for prostate cancer: results from the Canadian National Enhanced Cancer Surveillance System. Cancer Causes Control 1999;10(5):355-67.

Johnson KC, Hu J, Mao Y, and the Canadian Cancer Registries Epidemiology Research Group. Passive and active smoking and breast cancer risk in Canada, 1994-97. Cancer Causes Control. 2000;11:211-21.

Parkes R, Kreiger N, James B, Johnson KC. Effects on subject response of information brochures and small cash incentives in a mail-based case-control study. Ann Epidemiol 2000;10(2):117-24.

Srivastava A, Kreiger N. Relation of physical activity to risk of testicular cancer. Am J Epidemiol 2000;151(1):78-87.

Villeneuve PJ, Johnson KC, Hanley AJG, Mao Y, and the Canadian Cancer Registries Epidemiology Research Group. Alcohol, tobacco and coffee consumption and the risk of pancreatic cancer: results from the Canadian Enhanced Surveillance System case-control project. Eur J Cancer Prev 2000;9:49-58. 

Kenneth C Johnson, Environmental Risk Assessment and Case Surveillance Division, Cancer Bureau, Laboratory Centre for Disease Control, Health Canada, Tunney's Pasture, Address Locator: 0601C1, Ottawa, Ontario K1A 0L2; E-mail: Ken_LCDC_Johnson@hc-sc.gc.ca

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