ESTRO 2020 Abstract Book

S583 ESTRO 2020

package for social sciences (SPSS 22.0) and GraphPad Prism 6.01 (GraphPad Software, San Diego, CA, USA). Results Most of the metabolites involved in glycolysis, citric acid cycle and amino acid metabolism had major variations in RC patients compared to healthy individuals. Concretely, plasma glucose, pyruvate and glutamine concentrations were significantly higher in patients with RC. On the other hand, lactate, alanine, valine, leucine, fumarate, malate, αketoglutarate, glutamate and aconitate concentrations were significantly lower. NRCT significantly modified lactate, fumarate and glutamine concentrations, which tended to normal values. Hydroxybutyrate was the metabolite with the best discriminant capacity between patients before and after NRCT. In addition, the metabolic profile before NRCT was different in patients with acute toxicity and Dworak tumour regression grade 2 and 4 (Figure 1 and Table 1).

the control group after NRCT, meaning that the NRCT is also able to modify the metabolic profile of RC patients. PO-1104 Effect Of Neoadjuvant Radiochemotherapy On Activity Of Paraoxonase -1 In Rectal Cancer Patients E. Rodríguez 1,2 , J. Gomez 1 , A. Moreno 2 , J. Acosta 1 , L. Torres 1 , J. Trilla 1 , Y. López 1 , G. Baiges 2 , A. Hernández 2 , J. Camps 2 , J. Joven 2 , M. Arenas 1,2 1 Hospital Universitari Sant Joan de Reus, Department of Radiation Oncology, Reus, Spain ; 2 Institut d’Investigació Sanitària Pere Virgili- Universitat Rovira i Virgili, Unitat de Recerca Biomèdica, Reus, Spain Purpose or Objective Standard treatment for stage II and III rectal cancer (RC) is neoadjuvant or preoperatively radiochemotherapy (NRCT) followed by surgery. However, little is known about the effects produced by this oncological therapy on paraoxonase-1 (PON1), an antioxidant enzyme. The main objective of the project was to investigate changes in PON1 concentrations and activities, before and one month after NRCT administration in RC patients Material and Methods Thirty-two patients with locally advanced RC had been included in the study between 2014 and 2018. Blood samples were collected before and one month after NRCT. PON1 serum concentration was determined, as well as, PON and arylesterase activities. All statistical calculations and graph representations were performed with the statistical package for social sciences (SPSS 22.0, Chicago, IL, USA) and GraphPad Prism 6.01 (GraphPad Software, San Diego, CA, USA). Results When compared to healthy controls, PON1 concentration was decreased significantly in patients with RC and it increased one month after receiving the NRCT. Arylesterase activity was also decreased in patients with cancer and further decreased after the treatment. Conversely, PON activity was increased in cancer patients and, showed a non-significant trend to decrease after NRCT (figure 1). Moreover, PON1 concentration and its specific activities were able to differentiate patients with clinical nodal stages N1 and N2 diagnosis

Conclusion NRCT is able to modify the PON1-related variables in RC patients. One month after NRCT, values of PON1 concentration and enzymatic specific activities are able to return to similar values to those in control individuals. Moreover PON1 concentration and its specific activities could help in the diagnosis of clinical nodal stage.

Conclusion Results obtained in this study show clear alterations in glycolysis, citric acid cycle and amino acid metabolism in RC patients. Significant differences between the control and cancer groups were observed in the plasma concentrations of many metabolites. Lactate, fumarate and glutamine values returned to similar levels to those of

PO-1105 Interstitial PDR brachytherapy for the treatment of squamous cell anal carcinoma