Pancreatic cancer is, despite advances in science and medicine, one of the cancer diseases with the worst prognosis. Only one fifth of all patients are suitable for surgical treatment upon diagnosis, while the majority are already in advanced stages of the disease with metastases present. Due to the late onset of symptoms and their non-specificity, the disease represents an arduous diagnostic challenge, which is why more and more research is being directed towards new ways of treating and monitoring patients who are receiving therapy. Currently, various imaging tests and measurement of tumor markers are in routine use for this purpose. However, based on the findings of various studies, which proved that high levels of reactive oxygen compounds, changes in redox sequences and poor regulation of redox signalling are common indicators of cancer progression and resistance to therapy, more and more attention is being paid to markers of oxidative stress. Examining their concentrations in urine is an efficient and non-invasive way of determining how the redox balance has changed in the long term, as oxidized products that were formed during the repair of damaged DNA are excreted in the urine.
Based on previous research, this assignment aims to check the possibilities of using certain markers of oxidative stress in urine of patients with advanced pancreatic cancer. We decided for those because they are currently the most recommended or promising markers for long-term assessment of oxidative status. We selected the analytes 8-hydroxydeoxyguanosine, 8-isoprostane, dityrosine and hexanoyl lysine, which represent the products of oxidative damage to nucleic acids, proteins and lipids. The concentrations of selected analytes were measured using commercially available ELISA test kits. The results were compared to currently most widely used tumour markers CA 19-9 and CEA, as well as regarding the degree of disease progression and the effectiveness of the therapy received by the subjects. By analysing the data obtained during the research, we detected some permanent and characteristically changed concentrations of analytes in subjects with pancreatic cancer compared to available reference values. We found that the progression of the disease is often manifested as an increase in concentration of 8-hydroxydeoxyguanosine, 8-isoprostane, dityrosine and hexanoyl lysine, while effective therapy lowers concentrations. Based on data on various disease stages, we also proved that lower values of 8-hydroxydeoxyguanosine at the first sampling often predict a better survival. On the other hand, when compared to the tumour markers CA 19-9 and CEA, we found that the values of 8-hydroxydeoxyguanosine, 8-isoprostane, dityrosine and hexanoyl lysine do not always correlate with them, and only dityrosine showed a high proportion of correlations. Based on the results of the our research, it would be reasonable to introduce markers of oxidative stress in the urine into the monitoring algorithm of patients with advanced pancreatic cancer.
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