Lung cancer remains the single biggest cause of cancer death in Canada, accounting for a staggering quarter of all cancer deaths.

About 85 per cent of those cases can be chalked up to smoking. But doctors are noticing a troubling phenomenon that they can't yet fully explain: women are dying of lung cancer...and more of them have never smoked.

Faith Croxon is one of those women, the new face of lung cancer. An avid golfer who didn't smoked and avoided cigarettes all her life, she is now is battling advanced lung cancer.

"I was astounded, completely astounded," she says of the day when she got her diagnosis. "No one smokes in our house, or in our car. Our friends are not smokers. It just blew me away.

But it's not a complete surprise to cancer specialist Dr. Natasha Leighl of Toronto's Princess Margaret Hospital.

"In cancer centres, it certainly seems that we are seeing more lung cancer, in particularly younger women and in people who have never smoked," she says.

Lung cancer in what are called never-smokers is now the 10th most common cancer in Canada, and it's an illness that's seen more often in women.

Laurie Thomson is another non-smoker who's been diagnosed with lung cancer. She developed a cough last fall, which her doctors thought must be pneumonia. When she learned it was cancer, she was stunned.

"There is no history of cancer in my family. I have no history of lung cancer, and I never smoked, so why would it be lung cancer?" she says.

Doctors don't know what's behind the numbers. Radon, a radioactive gas that's released from rock and can seep into homes through the foundation, is thought to be the leading cause of lung cancer in non-smokers

Casual exposure to secondhand smoke likely also plays a role. But they also suspect pollution and perhaps genetics are playing a role – all factors that are not as easy to control as telling people to quit smoking.

"What makes lung cancer in never smokers worrisome is we don't know how to cut down that risk, who we should screen, or who we should watch to make that diagnosis earlier," says Dr. Leighl

The good news is that there are new treatments that seem to work well in non-smokers with lung cancer. Both Laurie and Faith are receiving these treatments and doing well.

Still they want to warn doctors not to ignore coughs that don't go away in non-smokers. Nor should they dismiss patients who are losing weight suddenly, or coughing up blood or who appear to have pneumonia that doesn't respond to antibiotics.

All of those could be signs that their patients might have something many think isn't possible.
