A Brock University researcher is part of a national team that has received funding from the Terry Fox Research Institute to investigate the relationship between air pollution and lung cancer.
Martin Tammemägi is co-leading the “Air Pollution and Lung Cancer Risk Prediction” project, one of four research areas in a larger $2.4-million, four-year project headed by the University of British Columbia’s Stephen Lam.
Tammemägi and his team will be creating a tool that predicts the risk of lung cancer in people who have never smoked, with a particular focus on evaluating the effects of air pollution.
The tool builds on the Brock Professor Emeritus of Epidemiology’s earlier lung cancer prediction model for smokers, which is being used to determine eligibility for lung cancer screening in Ontario, British Columbia and the United Kingdom. Other areas in Canada and Europe are considering implementing the model.
In this latest project, Tammemägi, along with the University of British Columbia’s Trevor Drummer, will extend the previous research to non-smokers.
“The proportion of lung cancers in individuals who never smoked is growing and in some parts of the world outnumber lung cancer in individuals who smoked,” he says. “Lung cancer in individuals who never smoked when considered as a separate group is the seventh leading cause of cancer deaths.”
In the lung prediction model for individuals who smoked, individuals are assessed using 11 factors, including the average number of cigarettes smoked per day, the number of years of smoking, whether they currently smoke, race/ethnicity, age, highest level of education obtained, family history of lung cancer, personal history of cancer and lung disease, and body mass index. These predictors are included in mathematical equations to estimate the risk of an individual getting lung cancer over time.
The new model will eliminate the criteria related to smoking and instead will include exposure to a class of airborne pollutants known as particulate matter or ‘PM2.5 ‘, which are tiny particles of soot, elemental and organic carbon, among other things. The impact of nitrogen dioxide and ozone will also be evaluated.
“Air pollution may lead to cancer by causing inflammation and oxidative stress of lung tissue and by inactivating cancer controlling genes,” says Tammemägi.
He says scientists study cumulative exposure to air pollution by linking individuals’ residential addresses to satellite image estimates of different air pollutants.
“Because historical records of such data have been stored, we can look back over 20 years to summarize cumulative air pollution exposures,” says Tammemägi.
To construct the new model, he and his team will be using patient data from studies produced by a variety of research groups in Canada, the U.K., Taiwan and the U.S.
As in the case of the model for individuals who smoked, the purpose of the lung cancer prediction model for individuals who did not smoke is to identify individuals who are at high risk for cancer so that they can be offered and benefit from lung cancer screening.
Low-dose computed tomography (CT) lung cancer screening for high-risk individuals detects earlier stages of cancer, which are often cured by surgery. Without screening, most lung cancers are detected at advanced stages, with most cases having poor survival.
Tammemägi says CT lung cancer screening has been shown to reduce lung cancer mortality by more than 20 per cent in high-risk individuals.
In Canada, lung cancer is the leading cause of cancer death, according to government statistics, with survival for lung cancer among the lowest of all types of cancer.
Research has shown lung cancers in non-smoking individuals are due to many reasons, including environmental air pollution. Increasing evidence suggests outdoor air pollution is a major cause of lung cancer in people who have never smoked, says Tammemägi.