RESUMO
INTRODUCTION: The aim of this study is to assess the significance of CEA, EGFR and hTERT as markers of occult tumor cells for predicting treatment outcomes in pancreatic cancers, as well as determining the cut-off values of these markers individually in peritoneal lavage. METHOD: The study compared 87 patients undergoing palliative operations (bypass surgery, biological sampling for subsequent oncological treatment) for either stage III or IV (UICC) pancreatic ductal adenocarcinomas with a control group of 24 healthy patients. Abdominal cavity lavage was performed at the beginning of the surgery in both groups, using 100 ml of physiological solution (phosphate buffered saline, pH 7.2). The samples were transported in bottles containing 1.5 ml 0.5 M EDTA and 10 ml of fetal bovine serum. Total RNA samples were all processed and purified by reverse transcription. Occult tumor cells in the peritoneal lavage were detected by the real-time RT-PCR method using CEA, EGFR and hTERT as markers of tumor cells. Another aim was to calculate the cut-off values of these markers. Statistical analysis was done using software R (www.r-project.org) and Statistica (StatSoft, Inc. USA). RESULTS: Mean expression of CEA, EGFR and hTERT in peritoneal lavage in the control group was 2501, 716749 and 104 copies of mRNA / mg RNA. Threshold, cut-off values were determined as the "mean + 2 times standard deviation". Absolute expression values were further normalized to expression of the house-keeping gene glyceraldehyde-3-phosphate dehydrogenase (GAPDH). After normalization, cut-off values of the tested markers were 4.89, 115.88 and 0.02 copies of mRNA/GAPDH mRNA. As regards absolute expression of the markers tested, only hTERT was able to statistically significantly (p<0.001) distinguish the analysed groups, where patients with advanced pancreatic adenocarcinoma had a higher expression of hTERT. Absolute expression of CEA or EGFR was not able to discriminate between the two groups. The more accurate normalized expression values of the test markers demonstrated a statistically significantly higher expression of hTERT (p<0.005) and CEA (p<0.001) in patients with advanced adenocarcinoma compared to the control group. CONCLUSION: Absolute hTERT expression in peritoneal lavage of patients with advanced pancreatic cancer was significantly higher compared to the control group.
