It is a simple test blow into a plastic bag, analyse it and see if the patient has esophageal cancer, a tumour in the windpipe.
(Subscribe: https://bit.ly/C4_News_Subscribe)
Trials are underway at Imperial College London with hopes the test could be rolled out in GP surgeries within five years.
Scientists say it could also be used for a range of other hard to detect cancers.
Follow us on Instagram / channel4news