Cancer of the gullet could be diagnosed with a cheap and simple sponge-on-a-string test, latest trial results show.
Swallowed and then retrieved from the mouth by pulling on the string, the Cytosponge capsule expands in the body to collect cells on its way out.
In tests on more than 1,000 UK patients, it was found to be well tolerated, safe and accurate at diagnosing Barrett's oesophagus.
One in 10 people with this condition later develops cancer of the food pipe.
In Barrett's, acid comes back up the food pipe from the stomach, which can cause symptoms such as indigestion and heartburn as well as changes in the normal cells that line the gullet.
Conventionally, doctors have diagnosed and monitored these patients for signs of cancer using biopsy - taking a small sample of cells - during a procedure called endoscopy, where a long, flexible tube with a camera is inserted down the throat.
But researchers from the Medical Research Council Cancer Unit at the University of Cambridge say the Cytosponge could replace this test.
Unlike endoscopy, Cytosponge can easily be used in GP surgeries and doesn't require any sedation, say Prof Rebecca Fitzgerald and colleagues.
As well as being less invasive, Cytosponge is also cheaper, costing £25 compared with the £600 cost of a traditional endoscopy.
The trial invited more than 600 patients with Barrett's to swallow the Cytosponge and to undergo an endoscopy. Almost 500 more people with symptoms like reflux and persistent heartburn did the same tests.
Many patients in the trial said they preferred it to endoscopy. More than nine in 10 patients were able to successfully swallow the capsule. Larger studies are now planned.
Dr Julie Sharp, of Cancer Research UK, the charity that funded the trial, said: "These results are very encouraging and it will be good news if such a simple and cheap test can replace endoscopy for Barrett's oesophagus.
"Death rates are unacceptably high in oesophageal cancer, so early diagnosis is vital."
Jacqui Graves, of Macmillan Cancer Support, said a less invasive test that hastened diagnosis would be welcome, but she said it would be some time before any such test would be available across the UK on the NHS.
The trial findings will be presented at the National Cancer Research Institute's annual conference in Liverpool this week.