In the first stage of intestinal metaplasia, the patient's damaged esophageal lining begins to grow the type of cells that line the intestinal wall rather than the normal squamous cells of the esophagus, explains Johns Hopkins Pathology. Over time, these cells replace the normal cells, resulting in a condition called Barrett's esophagus. Doctors characterize the next two stages as low-grade dysplasia and high-grade dysplasia, and consider these stages precancerous. These cells have an highly increased risk of becoming invasive carcinoma.
Doctors believe the process of intestinal metaplasia begins in response to gastroesophageal reflux, states Johns Hopkins Pathology. The regurgitation of stomach acid into the esophagus causes damage to its lining, which may lead to the growth of the wrong type of cells as the body attempts to repair the damage. These cells are less sensitive than the normal esophageal cells, so when patients reach this stage, they often feel relief from their symptoms. However, at this stage the patient's risk of esophageal cancer increases 30- to 125-fold over the general population.
By keeping patients with Barrett's esophagus under close medical monitoring, doctors are able to detect the appearance of cancerous cells before they have a chance to spread, says Johns Hopkins Pathology. Biopsies of the esophagus at the precancerous stages reveal genetic abnormalities that doctors recognize and can monitor.