Neoplastic precursor lesions of the upper gastrointestinal tract

Carcinomas of the oesophagus and stomach are major causes of morbidity and mortality in high prevalence regions, such as Eastern Asia. The incidence rate of adenocarcinoma of the gastro-oesophageal junction is also increasing in the US. Most carcinomas of the upper gastrointestinal (GI) tract develop in association with multifocal dysplasia and occur in patients with long-standing mucosal injury. Not surprisingly, increased utilization of endoscopy and mucosal biopsy in the evaluation of patients with upper GI tract symptoms has led to the frequent detection of mucosal atrophy, intestinal metaplasia and glandular dysplasia. Although appropriate classification of these lesions is straightforward in most cases, inflammation-induced epithelial changes may closely simulate, or mask, dysplasia, resulting in diagnostic confusion or precluding definitive diagnosis in some cases. Emerging evidence also suggests that specific molecular changes in non-dysplastic oesophageal and gastric mucosa herald the development of dysplasia and/or carcinoma, indicating that ancillary molecular analyses may play a role in the future management of high-risk patients. The purpose of this review is to discuss the clinical, pathological and molecular features of pre-cancerous lesions of the upper GI tract, as well as the potential pitfalls in their recognition and classification.