This new test could detect lung cancer in your breath

The 2012 horror film Hold Your Breath (now streaming on Peacock!) begins as many horror movies do, with a group of young people on their way to a weekend camping trip in the woods. Despite what you might expect, they don’t encounter a killer cryptid or escaped murderer, at least not in the conventional sense. The story is built upon an urban legend that a person can breathe in the spirits of the dead while passing a cemetery.

The movie suggests, in the bloodiest of terms, that a single breath could be the end of you, bur new research reveals that a single breath might actually save your life. Of course, every breath is important, you wouldn’t last long without them, but researchers from the Brown Cancer Center and the Department of Chemical Engineering at the University of Louisville may have developed a new test capable of detecting lung cancer in a lungful of air. That’s according to a recent study published in the journal PLOS One.

Lung cancer is among the most commonly diagnosed cancers, second only to breast cancer, and one of the most deadly. That’s because, like all cancers, the earlier you detect it the better your prognosis. Lung cancer is, unfortunately, famous for its late discovery. It’s estimated that about three quarters of lung cancer patients are diagnosed in the late stages of the disease.

At present, lung cancer is most often detected using CT scans among high risk individuals. There isn’t an easy and non-invasive way to detect the presence of lung cancer until it is often too late. A non-invasive, affordable, and easy to perform test could save an untold number of lives by identifying the disease in its early stages when the highest number of treatment options are still available.

Scientists wondered if they might be able to detect the presence of lung cancer in a person’s exhalations, because of a group of molecules known as volatile organic compounds (VOCs).

VOCs are compounds with a low boiling point and a high vapor pressure at room temperature. In simple terms, it means that they disperse as gases in ambient environments. They are the compounds responsible for the way things smell. When you peel an orange and that citrusy smell fills the room, those are VOCs. Those compounds aren’t only produced by citrus fruit, however. Humans make their own VOCs, and they can tell us something about where they came from. The idea is that different types of tissues and processes produce unique VOCs, with in turn create a sort of signature which can be picked up in the lungs. If we could identify a VOC signature for a particular disease, we might be able to develop breath tests for early diagnosis. The first step is identifying the signature.

To that end, researchers gathered a group of 414 participants broken up into several groups. First, there were 156 diagnosed lung cancer patients. Next, there was a group of 65 folks with benign pulmonary nodules, and a control group of 193 people. The control group was further broken up into 113 current or former smokers and 80 individuals who have never smoked.

One of the challenges of using VOCs to detect disease is that they can come from all over the body, by way of the blood stream, and make their way to the lungs. Detecting a particular compound in the breath doesn’t necessarily mean that compounds originated in the lungs. Researchers needed to find a precise compound or combination of compounds indicative of lung cancer and nothing else.

They leaned on the cohort of 156 lung cancer patients, and a machine learning algorithm, to identify potential biomarkers for the disease. They identified a suite of seven carbonyl VOCs — carbonyl refers to any molecule comprised of a carbon atom double bonded to an oxygen atom, with some other stuff hanging on — which appeared to be unique to the cancer patients. They then tested that signature against the larger group. The results of their study suggest that their VOC breath test accurately detects the presence of lung cancer 92% of the time, at least in their study group.

What’s unclear is if the test will work on a patient with an undiagnosed disease, particularly when asymptomatic and in the early stages. That’s the ultimate goal and it wasn’t necessarily demonstrated in the study. Further research is needed to replicate these results and confirm the test’s efficacy among the wider population. With any luck, the future of medical diagnosis will be as easy as breathing, and our collective improvement in treatment and prognosis will leave us all breathing a little easier.