ESTRO 36 Abstract Book

S675 ESTRO 36 _______________________________________________________________________________________________

EP-1254 DVH analysis of radiotherapy of upper gastrointestinal tumours: a model to predict toxicity. G.C. Mattiucci 1 , L. De Filippo 1 , N. Dinapoli 1 , L. Boldrini 1 , S. Chiesa 1 , M. Bianchi 1 , R. Canna 1 , F. Cellini 1 , G. Chiloiro 1 , F. Deodato 2 , G. Macchia 2 , C. Indellicati 1 , D. Pasini 1 , A.G. Morganti 3 , V. Valentini 1 1 Università Cattolica del Sacro Cuore -Policlinico A. Gemelli, Radiotherapy, Rome, Italy 2 Fondazione di Ricerca e Cura “Giovanni Paolo II”- Università Cattolica del Sacro Cuore, Radiotherapy Unit, Campobasso, Italy 3 Department of Experimental- Diagnostic and Specialty Medicine – DIMES- Università di Bologna- Ospedale S. Orsola-Malpighi, Radiation Oncology Center, Bologna, Italy Purpose or Objective Tolerance of small bowel is the dose limiting factor in radiation therapy for abdominal neoplasms. Bowel constraints for treatment planning in abdominal radiotherapy derive from scientific publications of pelvic tumors. This study has the aim to evaluate dose tolerance of small bowel and to provide a model detecting acute toxicities in patients with upper gastrointestinal (GI) cancer treated with radiotherapy. Material and Methods Patients with upper GI cancer treated between 2009 and 2016 with 3D-conformal or intensity modulated radiotherapy (IMRT) with or without concomitant chemotherapy were enrolled in this study. Nausea, vomit and loss of weight, as acute upper gastrointestinal (GI) toxicities, were scheduled using CTCAE v4.03 scale. In all patients small bowel loops, bowel bag, liver and stomach, if present, were contoured by a radiation oncologist on simulation computed axial tomography according to QUANTEC guidelines. Liver, PTVs, Small Bowel, Bowel Bag and Stomach were selected on Dose Volume Histogram (DVH) and their data were extrapolated. DVHs were analyzed for this structures using R statistical software (http://www.R-project.org). Results Data of 143 patients with a median age of 66 years (range 35-84), 79 (55,2%) resected and 64 (44,8%) unresected, were analyzed. All patients selected had primary tumour location cancer in upper GI tract such as pancreas (53%), biliary ducts (15%), stomach (26%), gallbladder (3%), gastroesophageal junction (3%). Prescribed dose ranged between 3000 cGy and 5580 cGy with fractionaction ranging between 180 cGy and 300 cGy. Most of patients were treated with 3D conformal radiotherapy (92%) and only 8% received IMRT. Fiftytwo (36,4%) patients reported no upper GI toxicity; on 27 (18,9%), 36 (25,2%) and 28 (19,5%) patients were observed respectively grade 1, 2 and 3 toxicity. No grade 4 toxicity was recorded. Fiftyone patients discontinued radiotherapy and 9 did not complete it, none of them because of GI toxicities. Analizing VDose for upper GI toxicity grade ≥ 2 on DVHs, small bowel loops V31.7, bowel bag V32.7, liver V35.6 Gy and stomach V31.5 Gy resulted as the parameter which most influenced upper GI toxicity (p<0.05). Univariate analysis for ≥G3 grade upper GI toxicity for all structures was not statistically significant (p>0.05). Univariate analysis showed no impact of surgery on upper GI toxicity while female sex and concomitant chemotherapy were associated with likely upper GI toxicity. Multivariate logistic model showed liver V35.6 as best and unique predictor of GI toxicity grade ≥ 2 (p<0.01). Relation between dose and toxicity is summarized in figure 1 as empirical cumulative density function plot. Conclusion In this investigation on patients treated for upper GI cancer, we recommend that V35.6 Liver (relative) should

be held to < 22% in order to get upper GI toxicity grade ≥2 probability below 15%. Further investigations should be done in order to observe significant dosimetric evaluation in patients with grade≥3 toxicity. EP-1255 Early clinical results for esophageal brachytherapy using a novel multi-balloon HDR applicator A.S. Taggar 1 , G.N. Cohen 1 , P.J. Brady 1 , J.J. Cuaron 1 , A. Wu 1 1 Memorial Sloan Kettering Cancer Center, Radiation Oncology, New York, USA Purpose or Objective Management of superficial primary and locally recurrent esophageal cancer (EC) in medically inoperable patients is complex. Endoluminal high-dose-rate (HDR) brachytherapy (BT) has shown mixed results in terms of toxicity and local control (LC). In this study, we assessed the outcomes and toxicities in a set of patients treated in a consistent fashion with a novel multi-balloon HDR applicator (E-app) using CT-based planning. Material and Methods Five patients were treated with the E-app between November 2015 and August 2016 in a single institution. Their records were reviewed retrospectively under institutional ethics board approval. All patients were treated with HDR brachytherapy using the E-app and 3D CT-based treatment planning, and received a total of 15 Gy in 3 weekly fractions prescribed to tumor volume. All treatments were completed as planned. Four patients had distal esophagus/GE junction tumors, and one patient had mid-thoracic tumor. For one patient who presented with squamous cell (SC) and another with and neuro-endocrine (NE) histology, BT was the primary treatment. Three patients had adenocarcinoma histology and were previously treated with primary chemo/radiotherapy (CRT); two had residual disease after primary CRT and one presented with recurrence 8 years after initial treatment with CRT. Two patients with residual disease received concurrent Capecitabine, whereas all others were treated with BT only. Results Patients’ median (range) age and KPS at the time of BT were 76.6 years (66.0–87.6) and 80 (40–90), respectively. Median length of treatment was 7.0 cm (5.5–9.0 cm). Median dose to the hottest 0.3cc within defined esophageal target volume (D 0.3cc ) was 34.5 Gy (31.8–36.6 Gy). D 0.3cc and V 100 of esophagus outside target volume were 14.7 Gy (9.1–21.9 Gy) and 0.8 cc (0.0–3.6 cc), respectively. Median follow-up from BT was 6.1 months (1.7–7.3 months). Observed toxicities included dysphagia (2 patients, grade 1 and grade 2), esophagitis (1 patient, grade 1) stenosis (1 patient, grade 1) and asymptomatic necrosis within the target area (1 patient, prior treatment with 50.4 Gy + FOLFOX chemotherapy); no grade 3 toxicity was observed. Repeat biopsy at 3 months’ post BT was done in 3 out of 5 patients: 2 (patients with SC and NE histology) had no evidence of disease and one had persistent disease. One patient developed metastatic disease and died without endoscopic assessment or biopsy after BT. Conclusion This is the first report of clinical outcomes using a novel multi-balloon HDR brachytherapy applicator (E-App). The E-App appears to provide a safe and effective method of delivering high doses of radiation to localized esophageal cancers. We observed low rate of toxicity with short follow-up and promising clinical and pathological responses in the settings of recurrent and residual disease.