Most tumours of the oesophagus, the tube that carries food from the mouth to the stomach, are caused by escaped stomach cells that have become cancerous.
The finding makes it more likely that cancers of the gullet, also known as the oesophagus or food pipe, could be prevented by a screening method that identifies former stomach cells, says Rebecca Fitzgerald at the University of Cambridge.
The most common form of oesophagus tumour in the UK and other high-income countries is an adenocarcinoma, found towards the stomach end of the tube.
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This kind of cancer was known to sometimes begin in a patch of abnormal cells, a condition known as Barrett鈥檚 oesophagus or just Barrett鈥檚. But whether this is always the case was unknown, as was the origin of the cells; aside from stomach cells, other suspects included cells lining the oesophagus, cells from glands within the oesophagus and embryonic cells found at the junction between the oesophagus and the stomach.
In the new study, Fitzgerald鈥檚 team took samples from these and other tissues from 20 deceased organ donors without gullet cancer and compared them with existing studies on 321 samples of oesophageal adenocarcinomas. They compared the cells in several ways, including by genetic sequencing and through the pattern of chemical modifications to their DNA.
The team found that all the adenocarcinomas had originally been stomach cells and had gone through a stage of being Barrett鈥檚 cells. They could have reached the oesophagus by migration or by spreading through multiplication, or both ways, says Fitzgerald.
About 1 in 10 people with Barrett鈥檚 eventually develop cancer of the oesophagus, so some have regular check-ups using a camera put down their throat. But most people with Barrett鈥檚 are unaware of it.
Having prolonged heartburn is a risk factor for Barrett鈥檚, so Fitzgerald鈥檚 team has developed a way to take a sample of cells from the oesophagus in people with heartburn. People swallow a small capsule attached to a string; in the stomach the capsule dissolves to release a 3-centimetre sponge, which is pulled back up by a nurse. On the way, the sponge collects cells lining the oesophagus, which can be tested.
Last year, that this method raised the identification of people with Barrett鈥檚 by 10-fold compared with usual care from a family doctor, which is to send people to hospital for a camera to be put down their throat under sedation, if their symptoms are concerning enough.
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