Never smoked before? You could still be at risk of lung cancer, experts say

Toronto resident Winhan Wong's lung cancer journey began in 2016, with a nagging cough that just wouldn't go away. 

A visit to his family doctor and a series of scans revealed the culprit: two litres of fluid in Wong's right lung and a three-centimetre tumour.

Though his doctors assumed otherwise based on the test results, Wong had never once smoked a cigarette in his life. 

“I was told that it was Stage 4,” Wong told White Coat, Black Art host Dr. Brian Goldman.

“There's one doctor that said I might have six months, and then my oncologist said I had basically one to 10 years.”

Lung cancer is the deadliest cancer in Canada, representing about 22 per cent of all cancer deaths in 2025. But rates as a whole have been falling, largely due to decreased smoking, which is linked with the majority of cases in Canada. Still, research shows more non- and never-smokers are getting diagnosed with lung cancer at the late stage.

Besides smoking, risks include poor air quality caused by pollution and wildfire smoke, occupational exposures like those for firefighters and construction workers, as well as cancer-causing gases like radon, found in homes due to out-of-date building codes.

"It's just heartbreaking," said Dr. Christian Finley, a thoracic surgeon at McMaster University, because I think it's that intersection of all their preconceived [notions that] this is a smoker's disease."

Definitions vary depending on the source, but the most recent Canadian Tobacco and Nicotine Survey, published in 2022, defines a never-smoker as someone who has never smoked a whole cigarette, or who hasn't smoked in the past 30 days and also has had fewer than 100 cigarettes — roughly four packs — in their lifetime. 

A former smoker — also called a non-smoker — is someone who hasn't had a cigarette in the past 30 days but has smoked at least 100 in their lifetime. 

Due to years of public health messaging, most Canadians are aware that inhaling cigarette smoke increases the risk of contracting lung cancer. 

Perhaps because of this, McGill University assistant professor Dr. Nicole Ezer says she encounters many patients who are surprised to learn how susceptible non- and never-smokers are to the disease. 

"[Never-smokers] may not be aware of all the risks associated with the development of lung cancer," said Ezer, director of the McGill Health Centre's lung cancer screening program.

Symptoms vary in intensity, but common signs include a persistent or worsening cough, shortness of breath, chest pains while breathing, difficulty swallowing and bloody mucus.