Aims: Accurate tumour classification is critical for meaningful epidemiological studies in the assessment of cancer incidence rates and trends. Differentiating primary gastric carcinoma from oesophageal carcinoma can be difficult, especially when tumours are large and involve both the oesophagus and stomach. Furthermore, adenocarcinomas of both organs typically are of intestinal histological type and arise in a background of intestinal metaplasia. Consequently, histological markers that reliably distinguish Barrett's-related oesophageal adenocarcinoma from gastric adenocarcinoma would be useful. Cytokeratins (CK)7 and 20 are cytoplasmic structural proteins with restricted expression that help to determine the origin of many epithelial tumours including those of the gastrointestinal tract. The aim of this study was to determine the utility of co-ordinate CK7 and 20 expression in the distinction of Barrett's-related oesophageal adenocarcinoma from gastric adenocarcinoma arising in a background of intestinal metaplasia.
Methods and results: CK7 and 20 immunostaining was performed on randomly selected surgical resection specimens from patients with Barrett's-related oesophageal adenocarcinoma (n = 30) and intestinal type gastric adenocarcinoma (n = 14) arising in a background of intestinal metaplasia. A CK7+ CK20- immunophenotype was demonstrated in 27 of 30 (90%) patients with Barrett's-related oesophageal adenocarcinoma and only three of 14 (21%) gastric adenocarcinomas. The sensitivity, specificity and positive predictive value of a CK7+/20- immunophenotype for a diagnosis of Barrett's-related oesophageal adenocarcinoma was 90%, 79%, and 90%, respectively.
Conclusions: A CK7+/20- tumour immunophenotype is associated with Barrett's-related oesophageal adenocarcinoma and may be useful in accurate tumour classification, thus facilitating improving epidemiological evaluation of tumours at the oesophagogastric junction.