The molecular biology of esophageal adenocarcinoma.
BACKGROUND
Barrett's esophagus is an acquired metaplastic change that occurs in the distal esophagus secondary to chronic gastroesophageal reflux. This premalignant condition forms the most important risk factor for developing esophageal adenocarcinoma, which is an extremely aggressive tumor with a 5-year survival rate of less than 25%. Carcinomas that arise in the setting of Barrett's esophagus are thought to develop as part of the metaplasia-dysplasia-carcinoma sequence.


OBJECTIVE
To review the current knowledge on the genomic alterations involved in the development of Barrett's esophagus and its progression to dysplasia and/or cancer.


RESULTS
Several changes in gene structure, gene expression, and protein structure are associated with the progression of Barrett's esophagus to adenocarcinoma. Accumulation of these changes seems to be essential, rather than the exact sequence of these changes. Multiple molecular pathways are involved and interact with each other. Alterations in tumor suppressor genes, amongst which p53 and p16, are early events in the metaplasia-dysplasia-adenocarcinoma sequence, followed by loss of cell cycle checkpoints. Ongoing genomic instability leads to cumulative genetic errors and thereby the generation of multiple clones of transformed cells.


CONCLUSIONS
Within the multistep process of esophageal adenocarcinogenesis, to date no single molecular marker came forward able to predict who will and who will not develop cancer in the setting of Barrett's esophagus. Instead, panels of markers need to be developed in the future allowing to indicate disease progression. Identification of crucial molecular pathways involved in esophageal adenocarcinogenesis would ultimately improve therapy and facilitate development of new treatment strategies.
Koppert
Linetta B
LB
Department of Surgery, Erasmus MC, University Medical Center, Dr. Molewaterplein 50, 3015 GE Rotterdam, The Netherlands.
Wijnhoven
Bas P L
BP
van Dekken
Herman
H
Tilanus
Hugo W
HW
Dinjens
Winand N M
WN
D000230:Adenocarcinoma / Q000235:genetics* / Q000473:pathology; D017209:Apoptosis / Q000235:genetics; D001471:Barrett Esophagus / Q000473:pathology*; D002869:Chromosome Aberrations; D019938:Cyclin D1 / Q000235:genetics; D004273:DNA, Neoplasm / Q000235:genetics*; D004815:Epidermal Growth Factor / Q000235:genetics; D066246:ErbB Receptors / Q000235:genetics; D004938:Esophageal Neoplasms / Q000235:genetics* / Q000473:pathology; D005764:Gastroesophageal Reflux / Q000150:complications; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008679:Metaplasia / Q000473:pathology; D018895:Microsatellite Repeats; D011230:Precancerous Conditions / Q000473:pathology; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000235:genetics; D016159:Tumor Suppressor Protein p53 / Q000235:genetics
D019938:Cyclin D1; D004273:DNA, Neoplasm; D004815:Epidermal Growth Factor; D066246:ErbB Receptors; D018719:Erb-b2 Receptor Tyrosine Kinases; D016159:Tumor Suppressor Protein p53