Dalhousie researchers working to assess environmental risks for lung cancer

A research team at Dalhousie University led by Robin Urquhart of the department of community health and epidemiology is looking at the biological factors for lung cancers among non-smokers.

Although smoking is the leading cause of lung cancer, one in five people diagnosed with the disease have never smoked. According to Urquhart, that number is increasing.

The research project has received $5 million from the Canadian Cancer Society to research the biological risk factors for lung cancer posed by environmental factors like radon, arsenic and air pollution.

Urquhart told CBC Radio's Maritime Noon host Bob Murphy Atlantic Canada has the highest rates of lung cancer in the country, and the highest mortality rates.

Their conversation has been condensed and edited for clarity and length. 

How common is it for non-smokers to be diagnosed with lung cancer?

It's probably more common than people think.

Lung cancer is most commonly linked to smoking. But the incidence of lung cancer is really increasing in people who've never smoked.

Today in Canada, it depends on where you live in the country but 20 to 30 per cent of all lung cancers that are diagnosed are diagnosed in people who have never smoked.

That means that at least one in five new lung cancers are in people who have never smoked.

How deadly is lung cancer then for those non-smokers?

Lung cancer, unfortunately, is still very deadly and that's because it's often diagnosed late.

Lung cancer is really interesting because if we detect it early survival rates rise really, really high. Early detection is really key because when it's diagnosed late, unfortunately the survival rates are not really high at all.

Here in the Atlantic provinces, we have the country's highest rates of lung cancer. We also have the highest death rates so it's a very important issue to us here I think.

Since smoking is so solidly linked to lung cancer, is that why much of the research into the disease up until now has been connected to smoking?

If I flip it around, 70 to 80 per cent of lung cancers are linked to tobacco use. That's why most of the research would be in that area for sure.

And yet we know there are other factors that can lead to lung cancer —  radon gas and arsenic and air pollution. How do we know those exposures pose a risk?

There has been work done just trying to understand the impact at a cellular level of, let's say, radon, arsenic, air pollution. We know that radon and arsenic are the two most important contributors to lung cancer in people who never smoked.

We also know in Canada the number one cause of lung cancer in people who never smoked is, in fact, radon. We also know that  Atlantic Canadians are among the most radon-exposed people in the world.

Radon has certainly been linked to lung cancer in people who have never smoked and smokers as well — if you've got that double sort of whammy then your risk increases quite a bit.

Your work then is to look at the biological factors that could make a person more vulnerable to these kinds of exposures, such as radon gas and arsenic and air pollution, how are you going about doing that?

There's a lot of different parts to this work.

It's a $5-million grant from the Canadian Cancer Society, which is quite a bit of funding to allow us to be able to look at these three exposures in many different ways.

Our goal really is to identify biomarkers of these exposures — radon, arsenic, air pollution exposures — by really coming at it from a number of different angles.

We've got access to a really great, what we call a lung tissue biobank, here — individuals who've already had lung cancer and have consented for more research to be done on those tissues.

We're really able to look at the damage that has happened due to environmental exposures and start to look at how that cancer is developed because of those exposures.

A lot of provinces now are starting to implement lung cancer screening programs for high-risk individuals and right now those are based on age and tobacco use.

If we can also  develop and be able to calculate a person's individualized lung cancer risk and then show that they're at a high risk and therefore they need screening as well, that's going to save lives.

What is the value in calculating the lung cancer risk? I suppose then people would have to take preventative steps?

Across the country there are provinces that are starting to put into place screening programs for people at high risk of lung cancer.

We're not screening everybody because the screening test is a low dose CT scan. There are harms that come along with screening people all the time and so we're only screening high risk people.

Those high risk criteria right now are based on tobacco like smoking history and age.

What we're trying to do is come up with the estimates of risk based on environmental exposures as well. So that can inform screening programs.

If you live in a part of the country or part of Atlantic Canada and have long term exposure to radon or or arsenic and we're able to measure that using something like your hair or toenail to be able to say, 'OK, you fit into that high risk category, you need to get screened for lung cancer.'

if you are deemed to have a higher risk than you would undergo more regular screening I suppose?

Just like any screening program, like the breast screening program or colorectal screening program, you're invited to screen at regular intervals to try and detect that cancer early. If you meet high-risk criteria, you'd be invited to be screened to see if you have lung cancer.