Using exhaled breath as a diagnostic tool
Electronic nose assesses whether immunotherapy is the right cancer treatment.
Exhaled breath could become an important diagnostic tool that guides future treatment of cancers and other diseases, Dutch researchers believe.
This follows successful trials at The Netherlands Cancer Institute of an “electronic nose” that detected chemicals in the breath of lung cancer patients and was then able to identify with 85% accuracy those who would respond to immunotherapy.
The eNose is a small device that contains sensors to detect volatile organic compounds (VOCs).
In trials with 143 patients with advanced non-small cell lung cancer it proved more accurate, the researchers say, than immunohistochemistry, the current gold standard for selecting patients likely to respond to certain immunotherapy treatments, which involves testing tissue samples.
"We hypothesised that exhaled breath analysis using eNose technology might be a non-invasive and rapid alternative to the current standard and would enable doctors to avoid treating patients with an immunotherapy to which they would not respond," says Rianne de Vries, joint first author of a paper published in the journal Annals of Oncology.
VOCs are present in about 1% of our exhaled breath, the researchers say, and can vary depending on metabolic processes that occur in the body or in parts of it, such as the lungs.
Each sensor in the eNose has its highest sensitivity to a different group of molecules. The sensor readings are sent directly to and stored at an online server for real-time processing of the data and for ambient air correction because exhaled air is influenced by inhaled air.
The measurement takes less than a minute, and the results are compared to an online database where machine-learning algorithms immediately identify whether or not the patient is likely to respond to therapy.
In this case, the technology was used as a guide not to do something: providing a warning that immunotherapy might be at best a waste of time, at worst counterproductive.
However, research leader Michel van den Heuvel sees great potential in the approach.
"We are convinced that this study merely scratches the surface,” he says. “It represents the first introduction of modern precision medicine, namely that molecular fingerprints can be easily obtained and quickly analysed on the spot.”