Scientists have found the strongest evidence to date that a condition known as Barrett’s esophagus is the starting point for all cases of esophageal adenocarcinoma—the most common type of esophageal cancer in the developed world—even when telltale signs of this pre-cancerous stage are no longer visible. The findings, published in Nature Medicine, could help improve screening for and early detection of esophageal cancer, the sixth-most deadly cancer, helping improve outcomes for the disease.

Cancer of the esophagus, including its most common form, esophageal adenocarcinoma (OAC), is on the rise in Western countries. It is difficult to treat because it is often caught at an advanced stage, when treatment options are limited. Scientists and doctors have known for some time that the development of esophageal cancer is linked with Barrett’s esophagus, which shows up in endoscopy as a pink patch on the surface of the esophagus. Barrett’s esophagus affects around one out of every 100 to 200 people in the United Kingdom.

Between three and 13 people out of 100 with Barrett’s esophagus will go on to develop esophageal adenocarcinoma in their lifetime. However, around half of OAC patients have no detectable Barrett’s esophagus when their cancer is found, raising doubts about whether it is always the precursor.