Modified classification for adenocarcinoma of the gastro-oesophageal junction.

BACKGROUND

Incidence of the gastro-oesophageal junction adenocarcinoma is increasing. Siewert's classification subdivides junctional adenocarcinomas anatomically. Cytokeratin (CK) 7 and 20 immunophenotypes differentiate Barrett's intestinal metaplasia (IM) from gastric IM. Comparing CK immunostaining with Siewert's classification may establish tumour origin and influence surgical choice.

METHODS

In this experimental study, 57 patients with gastro-oesophageal junction adenocarcinoma were subdivided endoscopically into 15 type 1, 26 type 2 and 16 type 3 adenocarcinomas. Representative biopsies were immunostained for CK7 and CK20.

RESULTS

Intestinal metaplasia was associated with type 1 adenocarcinoma in 12 of 15 patients, 80%; with type 2 in 13 of 26 patients, 50% and type 3 in 6 of 16 patients, 37.5%. All type 1 patients showed Barrett's CK7/CK20 phenotype within IM; type 2 a mixture: 69% (n=9) Barrett's CK7/CK20 and 31% (n=4) gastric CK7/CK20 whereas type 3 patients had a gastric CK7/CK20 pattern in 83% (n=5). Immunostaining within the adenocarcinoma was variable.

CONCLUSION

Siewert's type 1 adenocarcinomas express Barrett's CK7/CK20 pattern, type 3 a gastric CK7/CK20 pattern and type 2 tumours a mixture of Barrett's and gastric CK7/CK20 patterns within associated IM. CK immunostaining may refine Siewert's classification into oesophageal type 1 or gastric type 2 adenocarcinoma with IM.