ESTRO 38 Abstract book

S794 ESTRO 38

MEDLINE, EMBASE, OVID, and Cochrane database were used for the systematic search strategy. The computer search was supplemented with hand searches of reference lists. Only studies analyzing outcomes of patients re- treated where Re-I involved overlap with previous RT were taken into consideration. To determine the pooled toxicities rate (≥G3), pain relief, overall survival (OS), and local recurrence free survival (LRFS), a meta-analysis technique over single arm study was performed. Results Fourteen studies met the inclusion criteria, published between 2002 and 2017. Only four studies were prospective trials. Overall, 634 patients were analysed in the pelvis for Re-I within the pelvis for rectal cancer recurrences. Median follow-up from Re-I was 18.5 months (4.9 - 40 months). Four studies described the previous irradiation dose, delivered with a median dose of 50.4Gy (45-54 Gy) using a conventional fractionation. The mean time relapsed since previous irradiation was 28.8 months (22 - 47.4 months). Stereotactic RT technique was used for Re-I in 3 studies, carbon ions therapy in 1study, and external beam RT (EBRT) in the remaining studies (10 studies). Variable Re-I doses were prescribed: 25 Gy - 37.5 Gy. A hyper-fractionation schedule was employed in 8 of 10 EBRT studies. Concomitant chemotherapy was given in 501 patients (79%; 10 studies). Overall, 172 episodes of Grade ≥3 toxicity were reported; 52 were acute (severe diarrhea, moist desquamation, mucositis) and 120 were late toxicities (chronic severe diarrhea, fistula, small bowel obstructions, pelvic abscess, ureteral stricture, skin ulcerations). Factors influencing toxicities could be identified in surgical resection after Re-I, anterior tumor location, and a shorter retreatment interval of ≤ 24months. Pain relief, was evaluated in 10 studies: 88.3% (95% CI: 83.9–92.9%) of patients experienced pain relief. The pooled 2‐year OS rate (13 studies) was 54.6% (95%CI:47.8–62.3%). The pooled 2‐year LRFS rate (11 studies) was 49.4% (95% CI: 42.1–57.9%). Conclusion Based on the results of our analysis, rectal Re-I reported moderate rates of acute and late toxicities, although symptoms palliation and local control could be obtained. Prospective studies or large data collections seem to be necessary to define patients selection criteria to ensure maximal benefit of Re-I treatment approach. EP-1465 Impact of diabetes on outcome and toxicity of neoadjuvant (chemo)radiation for rectal cancer D. Bierbaumer 1 , S. Muench 1 , B. Haller 2 , D. Habermehl 1 , P.T. Pfluger 3 , K. Stemmer 3 , S.E. Combs 1 1 Klinikum rechts der Isar- Technical University Munich- Ismaninger Str. 22, Department of Radiation Oncology, 81675 Munich, Germany ; 2 Klinikum rechts der Isar- Technical University Munich- Grillparzerstr. 18, Institute of Medical Informatics- Statistics and Epidemiology- Medical School, 81675 Munich, Germany ; 3 Helmholtz Zentrum München- Ingolstädter Landstraße 1, Institute for Diabetes and Obesity, 85764 Neuherberg, Germany Purpose or Objective For patients with locally advanced rectal cancer, the German S3- guideline recommends neoadjuvant chemoradiation (nCRT) or short-course neoadjuvant radiotherapy (nRT) with before surgery to improve local control rates. While complete pathologic responses after neoadjuvant treatment are more commonly seen in patients without diabetes, there are conflicting results regarding the impact of diabetes on overall survival. Aim of this study was to compare oncologic outcome and toxicity between diabetic and non-diabetic patients undergoing neoadjuvant (chemo)radiation for rectal cancer. Material and Methods In total, 73 patients with locally advanced rectal cancer who underwent surgery after neoadjuvant chemoradiation

diagnostic imaging as magnetic resonance (MR: 85,71%), computed tomography (CT scan: 39,29%), and/or positron emission tomography (PET-CT: 35.71%). Co-registration with CT simulation is performed in 60.70% of the centers. An isotropic (73%), anisotropic (11,5%) or personalized (15,5%) margin is added for the for planning target volume. Doses are escalated by sequential boost in 6 centres up to 54-55Gy. Concomitant or simultaneous boost is delivered in 20 centers up to 55-60Gy (2.2- 2.5Gy/fraction). Intensity-modulated radiotherapy (IMRT) is used in 76,92% of the centers. Intra-operative Radiotherapy or peri-operative Brachytherapy is used in one center. Image-gated RT (IGRT) protocols are used in 22 centers (84,61%). Concomitant chemotherapy based on Capecitabine (57,69%) or 5-FU (42,31%), is administrated in 25 centers (96,15%).

Conclusion This survey illustrates the current status of dose intensification in preoperative LCRT in Italy. A high quality of dose escalation treatment was showed as highlighted by volume delineation the in the majority of centers based on MR imaging, and on the delivery using IMRT in more than 75%. Future clinical trials are needed to standardize this treatment approach aiming to improve treatment outcomes among locally advanced rectal cancer patients. EP-1464 A systematic literature review of rectal re- irradiation: tolerance and outcomes L. Caravatta 1 , F. Fiorica 2 , A.R. Alitto 3 , C. Rosa 1 , A. Nardangeli 3 , F. Munoz 4 , L. Bianco 4 , L. Giaccherini 5 , G. Timon 5 , F. Dionisi 6 , M. Massaccesi 3 1 “SS Annunziata” Hospital- “G. D’Annunzio” University, Radiation Oncology Unit, Chieti, Italy ; 2 University Hospital Ferrara, Department of Radiation Oncology, Ferrara, Italy ; 3 Fondazione Policlinico Universitario "A. Hematology Sciences, Rome, Italy ; 4 Azienda U. S. L. della Valle d'Aosta, Department of Radiotherapy, Aosta, Italy ; 5 Arcispedale Santa Maria Nuova - IRCCS, Radiation Oncology Unit, Reggio Emilia, Italy ; 6 Azienda Provinciale per i Servizi Sanitari- APSS, Proton Therapy Unit- Department of Oncology, Trento, Italy Purpose or Objective Standard treatment for locally advanced rectal cancer includes pelvic radiotherapy (RT). Re-irradiation (Re-I) could be required in case of local relapse, that may cause significant morbidity and symptoms impacting quality of life. Unfortunately, Re-I could produce severe normal tissues complications, with variable rate of toxicities. A systematic review, on behalf of the Association of Radiation Oncology (AIRO) study group for the re- irradiation, was conducted aiming to report the toxicity and outcome of pelvic Re-I for rectal cancer recurrences, in terms of local and/or lymph node disease. Material and Methods Gemelli"- Catholic University of Sacred Heart, Department of Radiological- Radiotherapy and