Researchers suggest air pollution be included as risk factor for lung cancer in non-smokers

Researchers from Vancouver have examined the impact that length of past exposure to air pollution has on lung cancer diagnosis.

In 2013, the International Agency of Research on Cancer classified outdoor air pollution and PM2.5 in outdoor air pollution as carcinogenic to humans, but the effects of air pollution exposure may take 15 to 20 years to be reflected in lung cancer development.

To assess the connection between pollution and lung cancer diagnosis, Dr Renelle Myers compared the cumulative three-year versus 20-year exposure in females with newly diagnosed lung cancer who have never smoked.

The researchers collected detailed information on the patients’ age, sex, race, country of birth, age of arrival in Canada (for foreign born Canadians), their occupation, family history of lung cancer, and secondhand smoke exposure. 

A detailed residential history from birth to cancer diagnosis for residences within Canada, and prior residences outside of Canada (for foreign born immigrants) were recorded. 

This geographical data included street and city address with postal codes, which allowed accurate linking of residential locations to satellite-derived PM 2.5 exposure data that were available from 1996 onwards.

Myers acknowledged that even a 20-year cumulative exposure does not capture childhood exposure and is an underestimate of lifetime exposure and depends on countries of residence.

Of the 236 female patients with lung cancer who had never smoked, all had a PM2.5 exposure greater than 5 ug/m3.

They found shorter term assessment significantly underestimated the cumulative exposure to PM2.5 prior to lung cancer diagnosis, especially among foreign-born Canadians.

‘Our study demonstrates the important of incorporating long-term cumulative exposure to ambient air pollutants in the assessment of individual lung cancer risk in combination with traditional risk factors,’ said Dr. Myers. ‘Research is needed regarding the best method to incorporate the effects of air pollution exposure prior to 1996 when accurate satellite data became available.  Our finding has important clinical implication in assessing lung cancer risk with global migration.’