ESTRO 36 Abstract Book

S279 ESTRO 36 _______________________________________________________________________________________________

Conclusion After SBRT for BM, our patients showed a clinically relevant improvement in QoL. At baseline, patients with pain report worse QoL and higher pain related scores compared to non-painful patients. SBRT on BM leads to a substantial reduction of pain scores contributing to a relevant QoL improvement in painful patients.

(QoL) becomes very important but studies evaluating QoL in these patients is lacking. This study evaluates the course of QoL in patients treated with SBRT for BM with validated pain and QoL questionnaires. Material and Methods At the University Medical Center of Utrecht, the PRESENT cohort is ongoing: a prospective cohort enrolling all patients with bone metastases candidate to radiotherapy. From this cohort, patients treated with SBRT were selected to evaluate QoL and pain. EORTC C15-PAL and BM22 questionnaires were administered at baseline, after 4, 8 weeks, 3, 6, and 12 months. BPI questionnaires were administered together with QoL questionnaires, and additionally after 2 and 6 weeks. Performance status and comorbidity index were scored at baseline. Pain flare was measured during treatment. Questionnaires were scored according to the scoring manuals and analyzed with descriptive statistics. QoL changes in time of ≥ 10 points were considered clinically relevant. Results Forty-nine patients with 35 spinal and 27 non-spinal lesions were included. Thirty-nine patients had oligometastatic disease. Median follow up was 6 months (range 1-31 months). Questionnaire return rates were 93% at baseline and 71-88% during follow up. At baseline, 25 patients had painful lesions with a mean BPI pain score of 5. During follow up, pain decreased to a score of 3 at 3 months, 2 at 6 months and 1 at 12 months (figure 1). In general, QoL based on EORTC C15-PAL and BM22 improved during follow up. No major deteriorations in functional and symptom scales were observed. At 12 months, further improvement of all functional and symptom scales was observed, except for dyspnea. Patients rated their global health status (GHS) in questionnaire EORTC C15-PAL. Overall GHS improved at 4 weeks, showed a decrease at 8 weeks and improved steady during follow up. GHS at baseline was lower in patients with pain than in patients without pain (58 vs 80 on a scale of 100). The difference in GHS between patients with and without pain reduced during follow up (difference of 22 points at baseline vs 2 points after 6 months) (Figure 2). Pain flare was reported in six patients, but no relevant differences in QoL in patients with and without pain flare were observed.

Symposium with Proffered Papers: Novel approaches in colorectal tumour control

SP-0527 State of the art in colorectal cancer radiobiology J. Bussink 1 1 UMC St Radboud Nijmegen, Radiation Oncology, Nijmegen, The Netherlands There is a limited amount of information on radiobiological data with respect to normal tissues for colorectal cancer. Experimental data that give an indication of a/b values are from studies dating back to the eighties. For acute toxicity the values are low (9-13) for late toxicity this was in the lower range (3-5). Late toxicity such as rectal bleeding is also strongly depending on irradiated volume but also on the topographical distribution of this volume, i.e. circumferential irradiation results in more toxicity than non-circumferential treatment. Tumor response is predominately hampered by the classical radiation resistance mechanisms such as intrinsic radioresistance, and hypoxia but also aberrant signaling by means of EGFR or VEGF may result in reduced radiation sensitivity. Several studies have investigated these parameters in the clinical and preclinical setting. These parameters can only be of relevance if it is possible to monitor these prior to treatment initiation. To assess the efficacy of interventions to address resistance ideally this would be monitored during treatment. Application of functional imaging by means of PET or MRI during treatment has been applied to limited extend in colorectal cancer. SP-0528 Immunobiology of gastro-intestinal tumours P. Huber 1 1 German Cancer Research Center DKFZ, Clinical Cooperation Unit Molecular Radiooncology, Heidelberg, Germany GI cancers are among the most frequent cancer in the western world. Many patients have high numbers of tumor specific T cells (cytotoxic T cells and T helper cells) in their blood and bone marrow. The molecular identification of tumor-associated antigens has led to the development of antigen-specific immunotherapy targeting these antigens which have so far failed to show efficacy in the clinic. Potential reasons for this lack of efficacy include the inefficiency of T cell activation in vivo, insufficient migration of cytotoxic T cells into the tumor, the choice of irrelevant antigens, induction or application of monovalent T cells. Here we will discuss the role of radiotherapy, the effective non- surgical local cancer therapeutic, in the immunobiology of GI cancer in the context of the microenvironment modifications, endothelial cells, intratumoral lymphocytes or dendritic cells, alone and in combination with checkpoint inhibitors, TLR agonists and other immune effectors. We will in particularly discuss the effects of low dose radiotherapy on T cell infiltration, macrophages and associated antitumor immune response in preclinical models and patients with operable liver metastases and pancreatic carcinoma.