Italian research found that an exhaled breath temperature over 34 degrees Celsius was strongly associated with a lung cancer diagnosis.
The researchers said that inflammation of the airways as a result of the condition could explain the rise in temperature.
The study was presented at the European Respiratory Society (ERS) congress in Munich, Germany, on Monday.
The study looked at 82 patients who had been referred for a full diagnostic test after an X-ray suggested the presence of lung cancer. Of these patients, 40 received a positive diagnosis of lung cancer.
Using a breath thermometer device, the researchers found that patients with lung cancer had a higher breath temperature than patients who did not have the disease.
Average normal breath temperature should be around 29 to 30 degrees Celsius. A higher reading – even by one or two degrees – may indicate that a patient’s airways are inflamed, which could be caused by an underlying condition, including lung cancer.
The study identified a cut-off value of 34 degrees Celsius as being strongly associated with a lung cancer diagnosis. Over 96% of patients with an exhaled breath temperature greater than this level received a lung cancer diagnosis in the study group, meaning the test could predict the condition with a high degree of accuracy.
Simple, non-invasive method
The technique offers clinicians a simple, non-invasive and inexpensive method of screening patients for lung cancer and other lung problems, the researchers said.
Lead author Professor Giovanna Carpagnano, from the University of Foggia, Italy, said: ‘Our results suggest that lung cancer causes an increase in the exhaled temperature.
‘This is a significant finding and could change the way we currently diagnose the disease. If we are able to refine a test to diagnose lung cancer by measuring breath temperature, we will improve the diagnostic process by providing patients with a stress-free and simple test that is also cheaper and less intensive for clinicians.’
But she added that breath tests alone do not currently ‘go far enough to give a diagnosis’ of lung cancer, and further tests are needed to fine-tune the process.
Professor Stephen Spiro, deputy chairman of the British Lung Foundation, said: ‘This research offers hope that in the future lung cancer may instead be diagnosed with less invasive and more straightforward methods.
‘While encouraging, this study looks only at established cases, and the real challenge will be to see if breath tests can identify lung cancer in its initial stages.’