Molecular abnormalities in pediatric barrett esophagus: can we test for potential of neoplastic progression?

Intestinal Metaplasia of the Esophagus in Children With Esophageal Atresia

OBJECTIVES

Patients with esophageal atresia/tracheoesophageal fistula (EA-TEF) can develop Barrett esophagus as a long-term consequence of their condition. Intestinal metaplasia (IM), a risk factor for developing adenocarcinoma of the esophagus, has not been well characterized in the pediatric population.

METHODS

Retrospective review of patients with EA-TEF followed at 3 academic pediatric centers between the years 1997 and 2014.

RESULTS

Among 542 children and adolescents, 1.3% (7 patients, 5 girls) were diagnosed with IM based on endoscopy and pathology. Six of the patients had EA-TEF type C, whereas the last patient had a "long gap" type A atresia. Patients were diagnosed with gastric metaplasia either before the IM diagnosis in 4 patients or concomitantly in 3. The median (range) age of diagnosis for gastric metaplasia was 7.9 (range 2-17.2) and for IM 10.9 (2-17.2) years. Gastroesophageal reflux (GER) symptoms were nonspecific. Five patients were on proton pump inhibitor therapy for symptomatic GER at the time of diagnosis of IM. 2 of the 7 patients had previously undergone Nissen fundoplication. One patient, who had undergone a Nissen fundoplication, was restarted on proton pump inhibitor once the diagnosis of IM was made. All patients had repeated endoscopy and dysplasia was not observed with a median follow-up of 1.7 (range 1-4.9) years.

CONCLUSIONS

IM occurs in patients with EA-TEF, some as young as 2 years. Therefore, early endoscopic surveillance should be considered in this GER-prone population.

Endoscopic findings of esophagogastric junction in children

Esophagogastric landmarks are recognizable in the same way both in children and in adults, and palisade-shaped vessels can be observed at the distal position of esophageal mucosa, even in infants. Few studies have been done in respect to Barrett's esophagus (BE) in children. Incidence of endoscopically suspected BE among all children undergoing esophagogastroduodenoscopy (EGD) is approximately 0.25-1.4%, but can be up to 9.7% in patients with gastroesophageal reflux disease (GERD). Some data suggest that BE is an acquired disorder and point to the possibility of a congenital component in combination with severe mucosal injury. Recent reports noted that multilayered epithelium (ME), which shows morphological and immunocytochemical characteristics of both squamous and columnar epithelium, is associated with goblet cell metaplasia in adult patients with columnar-lined esophagus. The role of ME in the development of intestinal metaplasia in children is uncertain. Furthermore, detailed mechanisms about how short-segment BE (SSBE) changes to long-segment BE (LSBE) are not yet well understood. Further studies are required to understand the pathological esophagogastric junction (EGJ) and BE in children based on reliable epidemiological data and analysis especially in children who have reflux symptoms. Better understanding of the pediatric EGJ and BE may allow improved diagnosis, monitoring, therapy and, therefore, prognosis of GERD-related disorders in adulthood.

Esophageal atresia: metaplasia, Barrett

Barrett's esophagus is characterized by the replacement of squamous epithelium by columnar epithelium that is intestinal metaplasia-positive or -negative in the distal esophagus. Gastroesophageal reflux disease, which is frequent and prolonged in esophageal atresia, probably plays a major role in the development of Barrett's esophagus through repeated mucosal damage. Long-term acid exposure contributes to carcinogenesis in Barrett's esophagus of intestinal type, but its effect on gastric metaplasia is less well defined. Recent studies have suggest that metaplasia arises in about 15% of patients with esophageal atresia, with a lag time to developing metaplasia from initial surgical correction of about 10 years. Preliminary data from an ongoing multicenter study including 88 patients with esophageal atresia aged 15-19 years showed gastric metaplasia in 42% of patients (29 fundic and 7 cardial metaplasia), while one patient presented intestinal metaplasia. Esophageal mucosal abnormalities can be observed in esophageal atresia patients at endoscopy despite the absence of symptoms. Whether prolonged, aggressive, acid suppression is beneficial in these situations remains to be determined. Barrett's metaplasia can be removed by endoscopic mucosal resection or destroyed with endoscopic ablative techniques, such as photodynamic therapy, radiofrequency ablation, and cryotherapy. The risk of developing esophageal carcinoma is still a controversial issue as only a few clinical cases have been reported in young adults with esophageal atresia. As late complications of esophageal atresia, particularly esophagitis and Barrett's esophagus, are increasingly being recognized, long-time systematic follow up of the esophageal mucosa including multistage biopsies is therefore required even in asymptomatic patients.

Clinical implications of molecular changes in pediatric Barrett's esophagus

Barrett's esophagus (BE) is a preneoplastic condition that predisposes to esophageal adenocarcinoma. Although data on the occurrence of BE in children are limited, recent studies have suggested an increase in the pediatric population. BE is thought to be a complex disease in which individual genetic predisposition interacts with environmental stimuli. Early premalignant clones produce biological and genetic heterogeneity, resulting in stepwise changes in differentiation, proliferation, and apoptosis, allowing disease progression under selective pressure. The value of endoscopic surveillance biopsy for dysplasia and carcinoma in patients with BE is controversial. Thus, the recognition of early and objective alternative risk markers, less susceptible of sampling error, will be of relevance in the management of BE patients. The possibility of performing molecular genetics on paraffin-embedded biopsies will expand our understanding of the natural history of BE and may lead to the use of biomarkers to inform treatment strategies.