Italian researchers have used a breath test to successfully diagnose colorectal cancer.

Cancer stinks—literally. Forproof, look no further than the fact that canines can detect lung cancer from a patient’s breath with 93 percent accuracy. Dogs can also successfully detect early-stage breast cancer, melanoma, and bladder cancer.

A dog’s sense of smell is up to 100,000 times more sensitive than a human’s, making them attuned to slight changes in a human’s breath that are present when tumors give off tiny amounts of volatile organic compounds (VOCs). Advancements in breath tests as diagnostic tools for cancer is the subject of a study published this month in the British Journal of Surgery.

In that study, lead author Donato F. Altomare, M.D., of the Department of Emergency and Organ Transplantation at the University Aldo Moro in Bari, Italy, successfully used breath analysis to detect the presence of colorectal cancer with 75 percent accuracy. (More than 50 specific compounds in exalted breath samples were also taken from a healthy control group for comparison.)

“The technique of breath sampling is very easy and non-invasive, although the method is still in the very early phase of development,” Altomare says. “Our study’s findings provide further support for the value of breath testing as a screening tool.”

Meanwhile, in the United States, physicians at the Cleveland Clinic in Ohio have helped pioneer a breathing test as a diagnostic tool for detecting lung cancer.

Peter Mazzone, M.D., a pulmonologist and director of Cleveland Clinic’s Respiratory Institute, calls the process the search for a “metabolic signature,” and hopes that breath testing will one day be used to recognize the chemical compounds and combinations of many diseases.

In 2011, Mazzone and Raed A. Dweik, director of Cleveland Clinic’s Pulmonary Vascular Program, used a breath test to sample 229 patients (92 with biopsy-proven lung cancer and 137 with indeterminate nodules). That study showed that the breath test used had up to an 89 percent accuracy rate (current breath tests are generally about 80 percent accurate), but it also discriminated among different types of cancer, notably between adenocarcinoma and squamous cell carcinoma.

“Our hope, within the next year, at the most, is starting studies in colon and breast cancer [detection]—anything that alters a person’s metabolic profile,” Mazzone continues.

Nir Peled, M.D., Ph.D., pulmonologist and oncologist at the University of Colorado Cancer Center, says, “The breath test could have significant impact in reducing unnecessary investigation and reducing the risk of procedure-related morbidity and [healthcare] costs. In addition, [breath tests] could facilitate faster therapeutic intervention, replacing time-consuming clinical follow-ups that would eventually lead to the same intervention.”

For the 2012 study led by Altomare, researchers specifically looked for 15 of 58 different compounds, each based on a selected VOC profile. (A probabilistic neural network was used to identify the pattern of VOCs that better discriminated between those with cancer and those in the healthy control group.)

Results showed that patients with colorectal cancer had a different selective VOC pattern than those in the healthy control group.

A person’s breath might one day be thought of as his or her fingerprint—completely individualized and able to reveal useful data about that person’s health. And though they are not yet widely used because they are so costly, breath tests are painless, quick, and non-invasive. When breath tests are eventually employed on a comprehensive basis, they will offer a treasure trove of information about a patient’s overall health.

Breath tests may one day be given regularly and used in diagnostics in the way blood tests are now, though breath tests will likely be less expensive. Eventually, breathing analysis could lead to earlier cancer detection, more accurate diagnosis, and fewer unnecessary biopsies.

According to the International Association for Breath Research, hundreds of different chemical compounds can be detected using breath tests, and each has a different signature that may one day be linked to a specific health condition or disease.

In a 2012 study conducted in Madrid, Spain, researchers used breath tests to search for patients with colorectal cancer, and presented their results at the Cancer Prevention Epidemiology Session of the 2012 American Society of Clinical Oncology (ASCO). In that study, breath tests correctly identified colorectal cancer in 82 percent of cases. In their ASCO presentation, study authors said, “Analyzing volatile organic compounds [in a person’s breath] could be a powerful diagnostic tool for the average-risk colorectal cancer population.”

Also in 2012, similar breath tests were used to study lung cancer at the Winship Cancer Institute of Emory University and Georgia Institute of Technology in Atlanta, Georgia. In that study, 14 unique VOCs were identified that were common to early-stage, non-small cell lung cancers.