Scientists have developed a cheap and non-invasive test that can measure the levels of five chemicals in the breath to detect cancers of the oesophagus and stomach with 85 per cent accuracy.       Together, stomach and oesophageal cancer account for around 1.4 million new cancer diagnoses each year worldwide.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 per cent.     Currently, the only way to diagnose oesophageal cancer or stomach cancer is with endoscopy -- an expensive, invasive method with 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," said Sheraz Markar from Imperial College London.     Previous research suggested that there are differences in the levels of specific chemicals -- butyric, pentanoic and hexanoic acids, butanal, and decanal -- in patients with stomach or oesophageal cancer and patients with upper gastrointestinal symptoms without cancer.In the new study, presented at the European Cancer Congress 2017 in The Netherlands, the team collected breath samples from 335 people, who were measured for levels of the five chemicals to see which ones matched to the 'chemical signature' that indicated cancer.        The results showed that the test was 85 per cent accurate overall, meaning that the breath test was good at picking up those who had cancer (80 per cent sensitivity) and was also good at correctly identifying who did not have cancer (81 per cent specificity)."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," Markar said.