Unseen risk

She doesn’t smoke. She never has.

There’s no obvious reason she should be here, sitting across from her physician, hearing the words lung cancer. And yet, this is becoming a more familiar story.

Across Atlantic Canada, physicians are seeing more patients diagnosed with lung cancer who have never smoked. It’s a shift that challenges one of the most established narratives in public health. For decades, lung cancer has been closely tied to tobacco. That connection remains. But it no longer explains everything.

Something else is shaping risk. And for many people, it’s something they would never think to look for.

At Dalhousie’s Faculty of Medicine, Dr. Graham Dellaire and his research team are working to understand what that “something else” is, and how to detect it earlier.

The risks we don’t see coming

Ask someone what causes lung cancer and the answer is immediate. Smoking.

Far fewer people will mention what’s in their well water. Or the air inside their home. Or smoke carried across provinces during wildfire season.

Yet these exposures are increasingly part of everyday life, particularly in rural communities.

Arsenic can be present in private wells. Radon, a naturally occurring gas, can accumulate in homes without any warning. Fine particulate matter from wildfire smoke, known as PM2.5, travels long distances and settles deep in the lungs. Over time, these exposures damage DNA, disrupt cellular processes, and trigger the kinds of changes that lead to cancer.

On their own, each risk can be easy to overlook. Together, they form what scientists call the “exposome” — the sum of environmental exposures that shape health over time.

The challenge is not just that these risks exist. It’s that we haven’t had a reliable way to measure their impact early enough to act.

Who gets missed

Lung cancer remains one of the most commonly diagnosed cancers in Canada and the leading cause of cancer death. Outcomes depend heavily on timing. When detected early, survival rates can exceed 80 percent. When found later, they drop below 20 percent.

Screening programs reflect what we have historically understood about risk. They are designed for people with a history of smoking.

But that leaves a growing number of patients outside the frame.

Nearly one in five lung cancers now occurs in people who have never smoked. In regions like Atlantic Canada, where environmental exposures are higher and populations are more rural, that gap becomes harder to ignore.

At this point, it’s not just about science. It’s about who gets included in screening, and who doesn’t.

A different approach to detection

Dr. Dellaire’s work is built around a simple but ambitious idea: detect the earliest signs of damage before cancer develops.

“For a long time, we’ve defined lung cancer risk by behaviour, primarily smoking,” says Dr. Graham Dellaire. “What we’re seeing now is that environment plays a much larger role than we once understood. The challenge is that these exposures don’t come with clear signals. By the time we detect cancer, the damage has already been done. Our goal is to make that early damage visible, so we can intervene sooner.”

The team is focused on identifying biomarkers, biological signals that reveal when lung cells have been affected by environmental exposure. If successful, these markers could function much like a cholesterol test, offering a way to assess lung cancer risk before symptoms appear.

To get there, the research brings together advanced microscopy, next-generation DNA and RNA sequencing, and artificial intelligence. High-resolution imaging allows scientists to observe how lung cells respond to arsenic and wildfire-related particles. AI is then used to analyze patterns across thousands of images and datasets, identifying changes that are far too subtle to detect otherwise.

Alongside this, the team is developing “human lung avatar” models, lab-based systems that replicate how lung tissue behaves in real conditions. These models make it possible to study exposure in a controlled environment and to test prevention strategies, including compounds derived from food and nutrition.

Why it matters here

This work is grounded in a very real regional context.

Atlantic Canada has some of the highest lung cancer rates in the country. Geography, environmental exposure, and rural living all play a role. At the same time, many of the people most affected are the least likely to meet current screening criteria.

That mismatch has consequences.

Earlier detection expands treatment options and improves survival. It also changes the experience of the disease itself, shifting it from late-stage crisis to something identified earlier, when more can be done.

It creates space for prevention.

From insight to action

One of the strengths of this work is what happens next.

Dr. Dellaire’s team is part of a broader national network of researchers, clinicians, and policy leaders. The goal is not only to identify environmental risk, but to translate that knowledge into screening guidelines, public health policy, and practical tools.

That includes informing how exposure limits are set, how risk is communicated, and how screening programs evolve.

As environmental conditions continue to change, this work becomes more urgent. Wildfire seasons are longer. Air quality is less predictable. Environmental exposure is becoming a more central part of how we understand health.

Looking ahead

We’re starting to think about cancer differently.

Less focus on reacting once disease appears. More focus on identifying risk earlier and intervening sooner.

Dr. Dellaire’s research sits right in the middle of that shift.

It offers a different way to understand lung cancer, not only as something to treat, but as something we may be able to detect earlier, track more precisely, and in some cases, prevent.

For the communities most affected, that shift is not abstract.

It means being seen in the data. 
It means being included in screening. 
And ultimately, it means more time.