Barrett's esophagus: model of neoplastic progression

Risk factors for neoplastic progression in Barrett’s esophagus

Barrett’s esophagus (BE) confers a significant increased risk for development of esophageal adenocarcinoma (EAC), with the pathogenesis appearing to progress through a “metaplasia-dysplasia-carcinoma” (MDC) sequence. Many of the genetic insults driving this MDC sequence have recently been characterized, providing targets for candidate biomarkers with potential clinical utility to stratify risk in individual patients. Many clinical risk factors have been investigated, and associations with a variety of genetic, specific gastrointestinal and other modifiable factors have been proposed in the literature. This review summarizes the current understanding of the mechanisms involved in neoplastic progression of BE to EAC and critically appraises the relative roles and contributions of these putative risk factors from the published evidence currently available.

Age effects and temporal trends in adenocarcinoma of the esophagus and gastric cardia (United States)

A number of hypotheses have been advanced to explain the rapid increase of the incidence of esophageal adenocarcinoma in the US. A major problem in identifying and understanding the nature of this increase is the difficulty in untangling age effects from temporal trends due to cohort and period effects. To address this problem, we have developed multi-stage carcinogenesis models that describe the age-specific incidence of adenocarcinoma of the esophagus and of the gastric cardia with separate adjustments for temporal trends. These models explicitly incorporate important features of the cancers, such as the metaplastic conversion of normal esophagus to Barrett's esophagus (BE). We fit these models separately to the incidence of adenocarcinoma of the esophagus and of the gastric cardia reported in the Surveillance Epidemiology and End Results (SEER) registry over the period 1973-2000. We conclude that the incidence of both cancers is consistent with a sequence that posits a tissue conversion step in the target organ followed by a multi-stage process with three rate-limiting events, the first two leading to an initiated cell that can expand clonally into a premalignant lesion, and the third converting an initiated cell into a malignant cell. Temporal trends in the incidence of both cancers are dominated by dramatically increasing period effects.