Abstract Book

S907

ESTRO 37

Results In total, 169 physicians (71 radiation-oncologists, 68 urologists and 30 medical oncologists) completed the survey. Detailed information on use of radiotherapy in the different clinical cases is presented in table 1. Guidelines most often followed were those from EAU (70%), NCCN (34%), institution (32%), ESMO (31%) and national guidelines (22%). Most reported reasons for non- adherence to guidelines were external barriers such as no referrals, cost/health economics (19%), no experience with RT for MIBC (13%) and negative experiences with RT in previous practice (13%). 37% always follow the guidelines and do not report barriers. Most often reported strategies to improve the awareness of existing guidelines are a compact summary of guidelines on the website of the national organization (54%), multidisciplinary oncological consultation (54%), an update of the existing guidelines by e-mail (53%), dissemination through symposia (44%) and a short overview of current trials by e-mail (39%).

of 6Gy with 6 fractions of 1.0Gy was delivered. The final outcome was assessed at least 6–8 weeks after completion of RT and in case of persisting pain or insufficient pain relief 6–12 weeks after the first RT course, a second RT series was recommended. Results This series included 57 women and 13 men, with a median age of 81 years (range: 42-91). The median pre- treatment value of VAS was 8 (range: 5-10). Fifty-eight painful sites underwent a second course of radiotherapy and median time interval between two treatments was 15 weeks (range: 8-68). With a median follow-up of 42 months (range: 2-118), median VAS at last visit was of 3 (range: 0-8). Median pain reduction for at least 3 months was reported in 74% (15-100%), median pain reduction for at least 12 months in 52% (18-100%). Von Pannewitz score resulted as “improved” in 89% of patients. No acute or chronic side effects were observed. Conclusion RT is an effective alternative for treatment of painful osteoarthritis with optimal response and low toxicity also in the long-term setting. EP-1689 Patterns of Intraosseous Recurrence After Stereotactic Body Radotherapy for Coxal Bone Metastasis K. Ito 1 , T. Shimizuguchi 1 , K. Nihei 1 , T. Furuya 1 , H. Ogawa 1 , K. Karasawa 1 1 Tokyo Metropolitan Cancer and Infectious diseases Center Komagome Hospital, Department Radiology MD., TOKYO, Japan Purpose or Objective To analyze the detailed pattern of intraosseous failure after stereotactic bodyradiation therapy (SBRT) for coxal bone metastasis. Material and Methods Patients treated with SBRT to coxal bone metastasis wereidentified by retrospective chart review. The SBRT doses were 30 Gy or 35 Gy in 5fractions. A margin of 5 to 10 mm was added to the gross tumor volume to createthe clinical target volume. We evaluated the presence or absence of intraosseous recurrenceusing magnetic resonance imaging. Intraosseous recurrences were assessed as'in-field” or 'marginal/out-of-field.” In addition, we measured the distance betweenthe center of the recurrent tumor and the nearest edge of the initial bone metastasisin cases of marginal/out-of-field recurrence. Results Seventeen patients treated for 17 coxal bone metastases were included.Median age was 64 years (range, 48-79 years). Coxal lesions involved the ilium in14 cases, pubis in 3, and ischium in 4 (3 lesions crossed over multiple regions). Patientsmost commonly had renal cell carcinoma (29.4%), followed by lung, hepaticcell, and colorectal cancers (23.5%, 11.8%, and 11.8%, respectively). Medianfollow-up after SBRT was 13 months (range, 2-44 months). Among all 17 cases, 7cases developed 8 intraosseous recurrences, including in-field recurrence in 1 caseand marginal/out-of-field recurrences in 7 cases. Median time to intraosseous recurrencewas 10 months (range, 2-35 months). Among 7 cases with marginal/out-offieldrecurrence, mean distance to the center of the recurrent tumor from the nearestedge of the initial bone metastasis was 34 mm (range, 15-55 mm).

Conclusion There is a lot of controversy regarding the place of RT in MIBC, with a clear variation between oncology professionals and a dependence of tumor-and patient- related factors. Barriers and facilitators to use RT for MIBC were defined which should be addressed, keeping in mind the actual gap in RT utilization and predicted increase in patients requiring RT for MIBC in the future. Funding Kom op tegen kanker grant EP-1688 Low-dose radiotherapy in painful degenerative osteoarthritis: long-term efficacy and outcomes. R. Hernanz de Lucas 1 , A. Montero 2 , D. Candini 1 , E. Fernandez 1 , S. Sancho 1 1 Hospital Ramon y Cajal, radiation oncology, Madrid, Spain 2 Hospital Clara Campal .Sanchinarro, radiation oncology, madrid, Spain Purpose or Objective To evaluate the long-term efficacy of low-dose radiation treatment (RT) in painful arthrosis. Material and Methods From January-2006 to December-2016, 128 degenerative osteoarthritis of the knee (84%), shoulder (8%), hands (4%) and hip (4%) from 70 patients underwent low-dose RT for palliative pain control. Visual analogue scales (VASs; from 0 to 10) and the subjective score according to von Pannewitz (improved/no change/worsened) were used for recording the symptomatic changes. A RT dose Electronic Poster: Clinical track: Other