The Breath Test That’s Changing Cancer Detection

The Breath Test That’s Changing Cancer Detection.

“Breathe in. Hold it. Now, exhale.”

I say that phrase almost daily, usually while reviewing a lung CT scan or prepping a patient for radiation. 

But what if that simple act — breathing — could do more than steady a scan?

What if your breath could lead to a lung cancer diagnosis?

As a radiation oncologist in Seattle — a city known for clean air, black coffee, and existential weather — I’ve spent years confronting cancer with biomarkers, biopsies, and beams. 

But a new technology has me raising an eyebrow and maybe even cracking a cautious smile: a breath test that detects lung cancer.

Yes, you read that right. 

In this piece, I’ll explain the fascinating science of volatile organic compounds, the dogs and machines trained to sniff out malignancy, and why this innovation could someday replace the dreaded needle.

And who knows? The next time you exhale, you might be exhaling your way toward a diagnosis — or even a second chance.

VOCs, Dogs, and Cancer Detection – The Breath Test That’s Changing Cancer Detection

​Volatile organic compounds (VOCs) are carbon-based chemicals that cells produce during metabolic processes. 

In cancer, these processes become abnormal, releasing unique VOC patterns into breath, urine, and sweat. 

These compounds serve as biomarkers, offering a non-invasive window into the body’s internal state.​

Dogs possess an extraordinary sense of smell, capable of detecting VOCs at concentrations as low as one part per trillion. 

Studies have demonstrated that trained canines can accurately identify prostate, lung, and breast cancers by sniffing breath, urine, or sweat samples.

For instance, research has shown that dogs can detect prostate cancer with over 97% sensitivity and specificity.

Electronic Noses

Inspired by canine olfaction, scientists have developed electronic noses (e-noses) that mimic this ability. 

These devices utilize arrays of chemical sensors to detect specific VOC patterns associated with various cancers. 

Recent advancements have enabled e-noses to identify lung cancer from exhaled breath, offering a non-invasive and potentially early diagnostic tool. ​

A New Electronic Nose

A new breath test using an “electronic nose” (eNose) shows real promise for detecting lung cancer — without needles, scans, or invasive procedures. 

This test analyzes the chemicals you exhale, which can carry unique patterns when cancer is present.

Researchers recently ran a large study across multiple hospitals involving 364 adults who had signs of possible lung cancer based on imaging or symptoms. 

Of these, about 6 out of 10 were ultimately diagnosed with lung cancer, while the rest had either no cancer or a different type.

SpiroNose

Each person in the study breathed into a device called the SpiroNose — a smart, cloud-connected tool designed to “sniff out” cancer-related compounds in the breath. 

The investigators did this maneuver after subjects had undergone bloodwork, lung function tests, and a PET-CT scan.

Study Details

The researchers tested two versions of the eNose model:

• One eNose model had already been developed and was used to assess all 364 patients.
• The other eNose model was a new version tailored for everyday clinical settings. Scientists trained it on part of the group (242 people) and then tested it on a separate group (121 people) to see how well it worked.

The researchers also paid special attention to people with COPD since this lung disease can make cancer harder to detect.

Takeaway Message – The Breath Test That’s Changing Cancer Detection

The original breath test (eNose) was very effective in detecting lung cancer in people with COPD (chronic obstructive pulmonary disease). 

The original breast test (eNose) correctly found cancer 95% of the time and gave the right “no cancer” result 72% of the time. 

Overall, it had an accuracy score (ROC-AUC) of 0.92, which is considered excellent.

Across all patients in the study (not just those with COPD), the original model still spotted most lung cancer cases (95% sensitivity) but wasn’t as good at ruling out people who didn’t have cancer — only getting that right about half the time (51% specificity). 

This statistic means it caught nearly everyone with cancer but had more false alarms.

A New eNose Version

To improve this, researchers created a newer version of the test tailored to people suspected of having lung cancer. 

In the final testing group, this new version still found 94% of cancer cases and was more specific about who didn’t have cancer (63% specificity). 

It had an overall accuracy of 0.83—better than the original in the general population.

Interestingly, the new model could also detect:

• 23% of people who had other types of cancer and
• 80% of people who had no cancer at all.

The updated eNose performance was consistent no matter what type of tumor people had, how far along their disease was, or their treatment hospital.

My Take – The Breath Test That’s Changing Cancer Detection

The bottom line? 

Breath analysis is getting closer to becoming a real tool in the clinic, but more studies are still needed before it can replace the current standards.

I want to remind you that we have a current recommended lung cancer screening approach for individuals at high risk for lung cancer.

• The only recommended screening test for lung cancer is low-dose computed tomography (also called a low-dose CT scan).
• Lung cancer screening is recommended only for adults who are at high risk for developing the disease because of their smoking history and age.

Specifics

The US Preventative Services Task Force recommends annual screening for lung cancer with low-dose computed tomography (LDCT) in adults aged 50 to 80 years who have a 20-pack-year smoking history and currently smoke or have quit within the past 15 years.

We discontinue screening once a person has not smoked for 15 years or develops a health problem that substantially limits life expectancy or the ability or willingness to have curative lung surgery.

The Bottom Line – The Breath Test That’s Changing Cancer Detection

Using volatile organic compounds (VOCs) to detect cancer could change how we approach diagnosis — making it faster, less invasive, and more patient-friendly. 

Instead of waiting for symptoms to appear or going through painful biopsies, we may soon be able to catch certain cancers early with something as simple as a breath test. The science is still evolving, but the potential is huge: easier access, earlier detection, and much less fear.

Screening for Lung Cancer
www.cdc.gov

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