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Conclusion As a developing nation, our obtained survival outcome showed a trend of improvement in comparison to other local results reported last decade, but still lower than the treatment outcomes of WT obtained in developed nations. We need more effort to improve our oncology care to get better results.

or multiple synchronous metastases. In this scenario only comfort measures or different palliative radiotherapy regimens are applied, from single doses to treatments lasting several weeks. The aim of this prospective study is to describe the preliminary results of our protocol of hypofractionated palliative radiotherapy in patients with non-operable rectal cancer. Material and Methods Patients with rectal cancer who were not candidates for surgical resection because advanced age, comorbidities, or multiple synchronous metastases at the time of diagnosis were considered eligible. Patients were immobilized in the prone position with a belly-board in order to reduce small bowel irradiation. To limit organ motion patient were instructed to empty the bladder and drink 500cm3 of water 45-60 minutes before CT simulation and before every treatment fraction. A conformal three-dimensional radiotherapy technique was planned to deliver to the primary tumor and the enlarged pelvic nodes a total dose of 39Gy in 13 sessions of 3Gy in 17 days. Symptomatic response 2 months after the end of treatment has been measured for bleeding and pain and acute toxicity were reported according to CTCAQv4.0 scale. Results From October 2016 to September 2017, 9 patients with a mean age of 84 years (71-90) were treated according to the protocol described above. The improvement / resolution of pain and bleeding were 100% (9/9) and 89% (8/9) respectively. No patient required colostomy during two months after radiotherapy. Acute toxicity ≤ grade 2 was 22% (genitourinary) and 44% (gastrointestinal), without grade 3 or 4 toxicities. No treatment was discontinued because toxicity. Conclusion Our protocol of hypofractionated palliative radiotherapy is effective palliating pain and bleeding, with acceptable toxicity. More patients and a longer follow-up of the survivors will provide us with more data on the improvement of the obstruction and no need for a colostomy, as well about time for symptomatic progression. EP-1649 Radiotherapy for osteolytic bone metastases from breast cancer: comparison with bone-modifying agent H. Tanaka 1 , M. Ito 1 , T. Yamaguchi 1 , K. Esaki 1 , M. Futamura 2 , F. Hyodo 1 , M. Matsuo 1 1 Gifu University, Radiology, Gifu, Japan 2 Gifu University, Surgical Onocology, Gifu, Japan Purpose or Objective Bone-modifying agents (BMA) are frequently used for treating patients diagnosed with bone metastases. BMAs are reportedly associated with a decrease in skeletal- related events (SREs). Although used to treat SRE, radiotherapy is primarily indicated for the prevention of pathological fractures. We evaluated the usefulness of radiotherapy for bone metastases treatment, in Oseteolytic bone metastases of the spine or pelvic bone from patients with breast cancer were evaluated in this study. Tomographic imaging was used to evaluate 35 lesions before and after radiotherapy, and 14 lesions before and after BMA treatment. Results Most lytic lesions treated with radiotherapy showed bone reformation (69%). Decreased fluorodeoxyglucose uptake comparison with BMA. Material and Methods

Electronic Poster: Clinical track: Palliation

EP-1647 Clinical features and efficacy of radiotherapy for bone metastases of unknown origin. N. Bychkova 1 , E. Khmelevsky 1 1 Gertzen Moscow Research Oncological Institute, Radiotherapy department, Moscow, Russian Federation Purpose or Objective The purpose of the current research was to study the efficiency of radiotherapy for bone metastases of unknown origin. Material and Methods Out of 686 cases of bone metastases, included in the long-term randomized trial in 16 (2,4%) it was impossible to identify the primary tumor site. The most frequent primary site was breast – 62,1%, both prostate and lung tumors were diagnosed in 8,3%, renal in 6,9%, colon in 2,6%. Separately we analyzed the mixed group of 19 patients represented by rare cases of bone metastases of stomach and liver cancer, head and neck tumors, gynecological tumors («Others»). Patient selection criteria for radiotherapy were pain, risk of pathological fracture/malignant spinal cord compression, increasing neurologic dysfunction. Irradiation volume included one anatomical area of the skeleton. Total dose was 13-26Gy in 2-4 fractions of 6,5 Gy. Results The average follow-up period was 70 months. The main characteristics of bone metastases of unknown origin such as gender, age, lesion length, risk of pathological fracture, pain intensity before treatment and effectiveness of EBRT were similar to the bone metastases of colon cancer and to the group «Others». Overall effectiveness of EBRT (сomplete and partial pain relief) for bone metastases of unknown origin was 81,2%, complete response rate attained in 43,8% of cases. Relative pain reduction was 65,4% and turned out to be one of the lowest between analyzed groups. It was significantly lower for bone metastases of unknown origin compared to breast cancer and melanoma (82,7% and 88,9%, р<0,05). Conclusion The results of the study make it possible to classify metastases in the skeleton of unknown origin as radioresistant lesions as well as bone metastases of renal, lung and colon cancer. More in-depth study of gastrointestinal tract in patients with bone metastases of unknown origin is needed. EP-1648 Palliative hipofractionated radiotherapy in non operable rectal cancer: preliminary results. J. Lozano Galan 1 , E. Rubio 1 , J. Solé 1 1 Consorci Sanitari de Terrassa CST, Radiation Oncology Department, Terrassa, Spain Purpose or Objective Many patients with rectal cancer were not candidates for surgical resection because advanced age, comorbidities,