- Currently, the only way to diagnose cancers of stomach and esophagus is through an endoscopy that involves risk of complications.
- A breath test that could accurately measure the levels of 5 different chemicals in the breath of patients with stomach and esophageal cancer, can be used as a new diagnostic measure.
- Cancer cells produce a mixture of chemicals, different from those of healthy cells, which can be detected using this breath test.
A test that measures the levels of five chemicals in the breath has shown promising results for the detection of cancers of the esophagus and stomach.
The results of the large patient trial, involving more than 300 patients, were presented at the European Cancer Congress 2017.
Stomach and esophageal cancers account for around 1.4 million new cancer diagnoses each year worldwide.
The number of new cases of stomach cancer was 7.4 per 100,000 men and women per year and the number of deaths was 3.3 per 100,000 men and women per year.
In 2013, there were an estimated 36,857 people living with esophageal cancer and 79,843 people living with stomach cancer in the United States.
There were an estimated 16,910 new cases of esophageal cancer and 26,370 new cases of stomach cancer in 2016 in U.S.
Ambiguous symptoms and late diagnosis, often bring down the level of the five-year survival rate for these two types of cancer to 15%.
The new research showed that the test could diagnose cancer with an overall accuracy of 85%.
Dr Sheraz Markar, an NIHR Clinical Trials Fellow from Imperial College London, under the supervision of Professor George Hanna, told the Congress "At present the only way to diagnose esophageal 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." Dr Marker added.
Previous research had suggested that there are differences in the levels of specific chemicals such as butyric, pentanoic and hexanoic acids, butanal, and decanal between patients with stomach or esophageal cancer and patients with just upper gastrointestinal symptoms but without cancer.
The new research, which is based on this research, aimed to test whether this 'chemical signature' could be the basis of a diagnostic test.
The research team collected breath samples from 335 people at St Mary's Hospital, Imperial College Healthcare NHS Trust; University College London Hospital and the Royal Marsden Hospital, London.
Among them, 163 had been diagnosed with stomach or esophageal cancer through an endoscopy and 172 showed no evidence of cancer when they had an endoscopy.
All the samples were analyzed with a technique called selected ion flow-tube mass spectrometry. This test accurately measures small amounts of different chemicals in mixtures of gases such as breath.
Researchers 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%.
The test was sensitive- which meant that it was good at picking up those who had cancer, it was also specific- which meant that it was good at correctly identifying who did not have cancer.
Dr Markar said "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 oesophagus 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."
The researchers plan to conduct a larger trial using the test in patients who are being given an endoscopy for gastrointestinal symptoms but not yet diagnosed with cancer.
This will assess the ability of the test to pick up cases within a group that is likely to contain only a small percentage of cancers.
Breath tests for other types of cancer, such as colorectal and pancreatic, are also being researched upon. This could be used as first-line tests in general practice surgeries.
- Cancer Stat Facts: Stomach Cancer - (https://seer.cancer.gov/statfacts/html/stomach.html)
- Cancer Stat Facts: Esophageal Cancer - (https://seer.cancer.gov/statfacts/html/esoph.html)