Breath Test Helps Detect Stomach and Esophageal Cancers
By Labmedica International staff writers
Posted on 17 Feb 2017
Image: Selected-ion flow-tube mass spectrometry (SIFT-MS) is a quantitative mass spectrometry technique for trace gas analysis of breath samples (Photo courtesy of Trans Spectra Limited).
A test has been developed that measures the levels of five chemicals in the breath has shown promising results for the detection of cancers of the esophagus and stomach in a large patient trial.
Together, stomach and esophageal cancer account for around 1.4 million new cancer diagnoses each year worldwide and both tend to be diagnosed late, because the symptoms are ambiguous, meaning the five-year survival rate for these two types of cancer is only 15%.
Scientists at Imperial College London and their colleagues collected breath samples from 335 people at different medical locations in London. Of these, 163 had been diagnosed with stomach or esophageal cancer and 172 showed no evidence of cancer when they had an endoscopy. The trial was based on the results of previous studies that suggested differences in the levels of specific chemicals (butyric, pentanoic and hexanoic acids, butanal, and decanal) between patients with stomach or esophageal cancer and patients with upper gastrointestinal symptoms without cancer.
The team analyzed all the samples were with a technique called selected ion flow-tube mass spectrometry, which is able to accurately measure small amounts of different chemicals in mixtures of gases such as breath. They measured the levels of the five chemicals in each sample to see which ones matched to the 'chemical signature' that indicated cancer. The results showed that the test was 85% accurate overall, with a sensitivity of 80% and a specificity of 81%. This means that not only was the breath test good at picking up those who had cancer (sensitivity), it was also good at correctly identifying who did not have cancer (specificity).
Sheraz R. Markar, MRCS, a clinical fellow and senior author of the study, said, “A breath test could be used as a non-invasive, first-line test to reduce the number of unnecessary endoscopies. In the longer term this could also mean earlier diagnosis and treatment, and better survival. Because cancer cells are different to healthy ones, they produce a different mixture of chemicals. This study suggests that we may be able detect these differences and use a breath test to indicate which patients are likely to have cancer of the esophagus and stomach, and which do not.” The study was presented at the European Cancer Congress held January 27-30, 2017, in Amsterdam, The Netherlands.