Risk factors for patients with lung cancer who have never smoked

To assess the connection between pollution and lung cancer diagnosis, Renelle Myers and their team 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 patient's age, sex, race, country of birth, age of arrival in Canada (for foreign-born Canadians), 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.

Cumulative exposure to PM 2.5 was quantified with a high-spatial-resolution global exposure model. The magnitude of three years versus 20 years of exposure was compared.

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, 83.3% were foreign-born; 71% were Asians. The mean years lived in a foreign country was 37.3 years. The mean age of lung cancer diagnosis was 66 years; 92.8% of them had adenocarcinoma and 55.9% were Stage III/IV lung cancer. For foreign-born Canadian females, only 2% had 3-year cumulative PM2.5 exposure of >10 ug/m3 whereas 20% had a 20-year cumulative PM2.5 of >10 ug/m3. All had a PM2.5 exposure greater than 5 ug/m3.