The Toronto lung cancer case-control study and SYNERGY project

Status: completed


The goal of this project was to examine associations between multiple occupational exposures and smoking within a Toronto-based lung cancer case-control study.

As well, data from this case-control study was contributed to the SYNERGY project. The SYNERGY project is an international study that has pooled data from lung cancer case-control studies performed across Europe and North America. These studies collected information on both occupational risk factors and smoking history. By pooling the data from these studies, a massive database was formed which allows complex interactions between exposures to be analyzed.


Workers are often exposed to multiple carcinogens in their workplace, or over the course of their working life. The effect of these carcinogens in combination is mostly unknown. Studying the interaction between multiple occupational carcinogens is difficult, as the low numbers of people exposed to two or more specific carcinogens results makes statistical analysis challenging. However, understanding the joint effects of occupational carcinogens is important for improving prevention efforts and ensuring appropriate compensation for workers who develop occupational cancer.


For the Toronto study, a questionnaire was given to lung cancer patients and controls to detail their job history, including main tasks and length of employment for all jobs held for at least 12 months. Information on smoking habits was also collected in order to be able to control for the impact of smoking on lung cancer risk.

The SYNERGY pooled analyses are being coordinated by the International Agency for Research on Cancer, the Institute for Prevention and Occupational Medicine of the German Social Accident Insurance, and the Institute for Risk Assessment Sciences at Utrecht University. For more information about the SYNERGY project, click here.


Toronto lung cancer case-control study:

SYNERGY pooled lung cancer study:



It is often difficult to show the effect of exposure to occupational carcinogens due to the huge effect of smoking on the risk of lung cancer, and the small numbers of people exposed to specific combinations of occupational exposures. Pooling data from a number of studies allows these interactions to be analyzed. Better understanding of the risks of occupational exposures and combinations of exposure could lead to targeted prevention initiatives and better compensation policies for workers with lung cancer.

Research Team:

Paul Demers (Co-PI)
John McLaughlin (Samuel Lunenfeld Research Institute) (Co-PI)
Jill MacLeod
Kate Jardine
Jack Siemiatycki (University of Montreal)
Kurt Straif (IARC)
Hans Kromhout (Utrecht University)
Roel Vermeullen (Utrecht University)
Susan Peters (Utrecht University)