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Expression of p53 protein in Barrett's adenocarcinoma and adenocarcinoma of the gastric cardia and antrum.

BACKGROUND/AIM
Most studies of esophageal and gastric adenocarcinomas have shown a very high rate of p53 gene mutation and/or protein overexpression, but the influence of the tumour site upon the frequency of p53 protein expression has not been evaluated (gastroesophageal junction, Barret's esophagus, and antrum). The aim of our study was to analyze the correlation between the selected clinico-pathological parameters, and p53 protein overexpression in regards to the particular tumour location.


METHODS
The material comprised 66 surgical specimens; 10 were Barrett's carcinomas, 25 adenocarcinomas of the gastric cardia (type II adenocarcinoma of the esophagogastric junction - EGJ), and 31 adenocarcinomas of the antrum. Immunostaining for p53 protein was performed on formalin-fixed, paraffin-embedded tissue sections, using the alkaline phosphatase antialkaline phosphatase (APAAP) method. The cases were considered positive for p53 if at least 5% of the tumour cells expressed this protein by immunostaining.


RESULTS
There was no significant difference observed between the studied groups in regards to age, sex, Lauren's classification and tumour differentiation. There was, however, a significant difference observed in the depth of tumour invasion between Barrett's adenocarcinoma and adenocarcinoma of the cardia compared with the adenocarcinoma of the antrum. Namely, at the time of surgery, both Barrett's adenocarcinomas and adenocarcinomas of the cardia, were significantly more advanced comparing with the adenocarcinomas of the antrum. Overexpression of p53 was found in 40% (4/10) of Barrett's adenocarcinomas, 72% (18/25) of adenocarcinoma of the cardia and 65% (20/31) of adenocarcinoma of the antrum. No significant differences in p53 expression in relation to sex, type (Lauren) of tumour, depth of invasion, lymph node involvement, or tumour differentiation were observed in any of the analyzed groups of tumours. Patients with more advanced Barrett's adenocarcinoma and in the cases of lymph node invasion revealed tendency for the greater p53 positivity compared with the early forms and lymph node-negative cases; however, this difference was not significant according to the statistical analysis. With regard to adenocarcinoma of the cardia, higher rates of p53 positivity were recorded in poorly differentiated, more advanced cases with lymph node invasion. Nevertheless, none of these differences was statistically significant. On the contrary, in the patients with adenocarcinoma of the antrum, greater p53 positivity was revealed in early forms without lymph node involvement, but the observed difference was not statistically significant.


CONCLUSION
No significant differences in p53 protein expression in terms of sex, type (Lauren) of tumour, depth of invasion, lymph node involvement, or tumour differentiation were observed in any of the analyzed groups of tumours (Barrett's adenocarcinoma, adenocarcinoma of the cardia and adenocarcinoma of the antrum).