Combined, cancers of the stomach and esophagus account for approximately 1.4 million new cancer diagnoses per year worldwide. However, both these cancers are likely to be diagnosed late, due to their ambiguous symptoms, which then results in very poor survival rates; the five year survival rates for these types of cancer is only 15%.
New research presented at the 2017 European Cancer Congress (27–30 January, Amsterdam, The Netherlands), involving more than 300 patients has demonstrated that a breath test measuring the levels of five chemicals in the breath, could diagnose stomach and esophageal cancer with an overall accuracy of 85%.
Sheraz Markar (Imperial College London, UK) commented to the congress: “At present the only way to diagnose oesophageal cancer or stomach cancer is with endoscopy. This method is expensive, invasive and has some risk of complications. 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.”
The study built on previous research that highlighted differences in the levels of five specific chemicals (butyric, pentanoic and hexanoic acids, butanal, and decanal) among patients with esophageal or stomach cancer and patients without cancer, but with gastrointestinal symptoms. The new trial investigated whether the aforementioned “chemical signal” which is thought to be characteristic of cancer could be the basis of a diagnostic breath test.
As part of the trial, researchers collected breath samples from 335 people from St Mary’s Hospital (London, UK); University College London Hospital (London, UK); and the Royal Marsden Hospital (London, UK). 163 people from the cohort were diagnosed with either esophageal or stomach cancer, with the remaining 172 showing no evidence of cancer post endoscopy.
Researchers analyzed the levels of the five chemicals in each sample via ion flow-tube mass spectrometry, as to observe which samples corresponded to the chemical signature associated with cancer. The results demonstrated that the test was overall 85% accurate, with 81% specificity and 80% sensitivity.
“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. However, these findings must be validated in a larger sample of patients before the test could be used in the clinic” Marker concluded.
The team will continue with a larger trial over the next three years, utilizing the test with patients who are not yet diagnosed with cancer, but receiving an endoscopy as a result of gastrointestinal symptoms. This will allow researchers to assess the tests ability to detect cases in a demographic that is likely to only contain a small percentage of cancers. The group is also developing breath tests for cancers such as colorectal and pancreatic cancer, which could potentially lead to the tests being used first-line in general practice surgeries.