Introduction: We have investigated aberrant methylation of genes CDH1, RASSF1A,
MLH1, N33, DAPK, expression of genes hTERT, MMP7, MMP9, BIRC5 (survivin), PTGS2, and activity
of telomerase of 106 gastric tumor samples obtained intra-operatively and 53 gastric tumor samples
from the same group of patients obtained endoscopically before surgery. Biopsy specimens obtained
from 50 patients with chronic calculous cholecystitis were used as a control group. Together with tissue
samples obtained from different sites remote to tumors, a total of 727 samples have been studied.
The selected parameters comprise a system of molecular markers that can be used in both diagnostics
of gastric cancer and in dynamic monitoring of patients after surgery. Special attention was paid to the
use of molecular markers for the diagnostics of malignant process in the material obtained endoscopically
since the efficacy of morphological diagnostics in biopsies is compromised by intratumoral heterogeneity,
which may prevent reliable identification of tumor cells in the sampling. Our data indicated
that certain molecular genetic events provided more sensitive yet specific markers of the tumor.
Conclusion: We demonstrated that molecular profiles detected in preoperative biopsies were confirmed
by the material obtained intra-operatively. The use of endoscopic material facilitates gastric
tumors pre-operative diagnostics, improving early detection of gastric cancer and potential effective