EXPRESSION OF ABERRANT p53 PROTEIN IN GASTRIC CANCER Authors: Tatjana Bogdanova1, Mareks Marčuks1, Ilze Štrumfa1 1Department of Pathology, Riga Stradins University, Riga, Latvia

Introduction Gastric cancer is one of the most common cancers worldwide.[1] It has complex molecular pathogenesis. The tumour suppressor gene TP53 has an important role in cell cycle regulation and initiation of tumour genesis.[2] Carcas L.P.; J Carcinog, 13, 2014, 14: doi: 10.4103/1477-3163.146506 Lazar D. et al.; Rom J MorpholEmbriol, 51, 2, 2010, 249-257

Objectives To detect the frequency of p53 expression in gastric cancer by relevant clinical and pathological parameters such as cancer grade and mural invasion.

Methods Study group: retrospective design; consecutive potentially radically operated gastric cancer cases; from 2011 to 2014; from a single university hospital.

Methods Histological type, local cancer spread, grade of differentiation and lymphnode status were evaluated according to the World Health Organisation classification (2010).

Methods The expression of p53 protein was detected by immunohistochemistry. Case was considered positive if at least 10% of tumour nuclei were positive. Unpaired T test was further applied for statistical analysis and p<0.05 was considered significant.

Photo No2.: T.Bogdanova Photo No1.: M.Marčuks Photo No3.: M.Marčuks

Results The resulting group included 103 patients: 66 men (64.1%; 95% CI: 54.5 to 72.7); 37 women (35.9%; 95% CI: 27.3 to 45.6). Patient’s age ranged from 24 to 88 years: Mean 67.0 years (95% CI: 57.8 to 76.0). Histological type: 83 adenocarcinomas (80.6%; 95% CI: 71.8 to 87.1); 20 signet ring cell cancers (19.4%; 95% CI: 12.9 to28.2)

Results Positive p53 expression: 48 cases (46.6%; 95% CI: 37.3 to 56.2); 42 adenocarcinomas (50.6%; 95% CI: 40.1 to 61.1); 6 signet ring cell cancers (30.0%; 95% CI: 14.3 to 52.1); p= 0.029. The nuclear reactivity was homogenous. Low p53 expression was observed in signet ring cell cancers.

Results Local cancer spread (pT2 versus pT3 versus pT4) p=0.705. Lymphnode status (positive versus negative for metastases) p=0.117. Cancer grade of differentiation (moderate versus high grade) p=0.314. Age p=0.459. Gender p=0.352.

Discussion The expression of aberrant p53 protein was observed in 46.6% of surgically treatable gastric cancer cases. The signet ring cell cancers showed less frequent p53 protein expression (p=0.029).

Discussion The p53 expression is homogeneous by the immunohistochemical distribution. Neither demographic nor such histological data as the local tumour spread, lymph node status or cancer grade showed differences by p53 protein expression suggesting also demographic, grade- and stage-related homogeneity. This makes p53 protein well-suitable for anti-cancer immunization. However, complex treatment must be applied due to intermediate expression rate.

Thank you for your attention! Any questions?