ESTRO 2020 Abstract Book

S557 ESTRO 2020

PO-1046 Treatment outcomes of liver metastasis treated with stereotactic body radiotherapy O.C. Güler 1 , B.A. Yıldırım 2 , C. Onal 2 1 Baskent Universitesi Tip Fakultesi- Adana Hastanes, Radiation Oncology, Adana, Turkey ; 2 Baskent University, Radiation Oncology, Adana, Turkey Purpose or Objective To analyze the outcomes of liver metastasis (LM) treated with stereotactic body radiotherapy (SBRT) and systemic treatment in oligometastatic patients. Material and Methods The treatment outcomes of 65 patients (93 LM’s) with oligometastasis (£5 metastases) at the time of LM or who became oligometastatic after systemic treatment were assessed. Most of the metastasis (57 patients [88%]) were diagnosed by 18-fluorodeoxyglucose positron emission computerized tomography (FDG-PET-CT). A total of 54 Gy delivered in 3 fractions in most of the patients (54 patients [83%]) between April 2013 and April 2019. The local control (LC), overall survival (OS), and progression-free survival (PFS) rates were calculated using Kaplan-Meier analyses. Results Median age and follow-up time were 52 years (range 24 – 78 years) and 13.7 months (range 1.7 – 48.9 months), respectively. Among 65 patients, 39 (60%) had solitary LM while 24 patients (37%) had two lesions and 2 patients (3%) had three lesions. Most of the patients [49 patients (75%)] developed LM during the follow-up of initial treatment, while only 16 patients (25%) had LM at the time of first diagnosis. More than half of the patients (37 patients [57%]) had breast cancer as primary, 11 patients (17%) had colorectal cancer, 6 patients (9%) had lung cancer and 11(17%) patients had other (cervical, melanoma, renal cell, stomach, sarcoma, hepatocellular, ovarian and pancreatic) primaries. 41 patients (63%) had another organ metastasis besides LM [lung 11 (17%), bone 16 (25%) and multiple 38 (58%)], only LM was observed in 24 patients (37%). At last visit, 36 patients (55%) had disease recurrence, median 8.7 months (range 1.3 – 46.5 months) after completion of liver SBRT. 8 patients (12%) had local and distant recurrences, and 4 of them (6%) had isolated LM recurrence. Median OS and PFS were 30.8 months [95% confidence interval (CI) 19.9 – 42.7 months]) and 11.6 months (95% CI; 9.1 - 14.0 months), respectively. The 1- and 2-year LC rates were 93% and 80%, respectively. In uni- and multivariate analysis, no significant prognostic factors, including disease extension, size of metastasis, number of liver metastasis and timing of liver metastasis, affecting survival and local control were found. In patents with solitary LM, PFS was significantly better than compared to patients with additional metastasis beyond liver (17.8 mo [12.8-22.8 mo] vs. 10.4 mo [7.9 mo-12.9 mo]); p:0.034). No patients experienced Grade 4 or 5 toxicity; furthermore, only two patients experienced rib fracture 6-8 months after completion of treatment, and one patient had a duodenal ulcer. Conclusion This study is one of the first to evaluate the feasibility of SBRT to LM patients in a larger oligometastatic patient cohort. Our findings support that the liver SBRT is a feasible and safe method for LM with excellent LC and acceptable toxicities. PO-1047 GemOx with low-dose RT and SBRT for locally advanced pancreatic cancer: a prospective trial B. Meduri 1 , G. Aluisio 1 , E. D'Angelo 1 , M. Vernaleone 1 , C. Tata 1 , F. Gelsomino 2 , A. Spallanzani 2 , R. Ballarin 3 , G. Luppi 2 , F. Di Benedetto 4 , F. Lohr 5 1 Azienda Ospedaliero-Universitaria di Modena, Oncology Department - Radiation Oncology Unit, Modena, Italy ; 2 Azienda Ospedaliero-Universitaria di Modena, Oncology Department - Medical Oncology Unit, Modena, Italy ; 3 Azienda Ospedaliero-Universitaria di Modena, Department of Surgery - Hepato-Pancreato-Biliary and

Liver Transplant Unit, Modena, Italy ; 4 Università di Modena e Reggio Emilia, Department of Surgery - Hepato-Pancreato-Biliary and Liver Transplant Unit, Modena, Italy ; 5 Università di Modena e Reggio Emilia, Oncology Department - Radiation Oncology Unit, Modena, Italy Purpose or Objective To evaluate safety and local control (LC) of an induction chemotherapy (CHT) regimen combined with low-dose radiotherapy (LDR) used as a chemo-enhancer and followed by stereotactic body radiotherapy (SBRT) in locally advanced pancreatic cancer (LAPC) Material and Methods Patients (pts) with non-metastatic inoperable LAPC were enrolled on a prospective study (NCT02416609). Four CHT cycles with Gemcitabine and Oxaliplatin (day 1-8 of a 21- day cycle) concurrent with LDR were administered; LDR was delivered on days 1 and 2, 8 and 9 of each CHT cycle, twice a day, using eight doses of 40 cGy each. If no systemic progression was observed after CHT-LDR, pts received 3 fractions of 8, 10 or 12 Gy (total dose 24-36 Gy) of SBRT based on tumor location in relation to stomach and duodenum. 4D-CT with oral and i.v. contrast was used for treatment planning and IGRT-IMRT for delivery. Patients were followed up every 3 months. LC was evaluated at 6 months after SBRT and toxicity was scored according to CTCAE v4 Results Between February 2014 and March 2019 we enrolled 20 pts. All pts received four CHT cycles, except one who received only 3 cycles, because of heart disease. Three pts developed distant metastasis after induction CHT, 17 received SBRT. Total SBRT dose was: 36 Gy (3 pts), 30 Gy (6 pts) and 24 Gy (7 pts). At present 3/20 pts underwent resection without complications. Ten pts (50%) developed acute G3 or greater haematologic toxicity, 1 pt (5%) developed acute G3 gastrointestinal pain, no further G3 or greater nonhematologic acute toxicity was observed. One pt (5%) developed G2 gastric ulcer and G2 gastric haemorrhage that were medically managed, 1 pt developed G3 late diarrhea and 1 pt died for an intestinal perforation. Twelve pts were evaluated for local control; at 6 months LC was 100%. Five patients were not evaluable for LC; 1 pt recently ended SBRT (1 month ago) and four pts died before 6 months from SBRT (three with no local progression and one with local and distant progression) Conclusion Induction CHT regimen combined with LDR used as a chemo-enhancer and SBRT in three fractions resulted in a low rate of side effects. Stereotactic RT on pancreatic disease showed excellent LC rate at 6 months. We wait for enrolment conclusion to report survival results PO-1048 Postoperative complications and margins status after neoadjuvant SBRT for pancreatic cancer N. Simoni 1 , S. Paiella 2 , R. Micera 1 , T. Giuliani 2 , S. Guariglia 3 , E. Zivelonghi 3 , A. Di Gioia 2 , L. Addari 2 , G. Malleo 2 , R. Salvia 2 , C. Bassi 2 , R. Mazzarotto 1 1 University of Verona Hospital Trust, Radiation Oncology, Verona, Italy ; 2 University of Verona Hospital Trust, General and Pancreatic Surgery, Verona, Italy ; 3 University of Verona Hospital Trust, Medical Physics, Verona, Italy Purpose or Objective Total Neoadjuvant Therapy (TNT) is an emerging approach for pancreatic cancer (PC) patients, but a consensus regarding its ideal structure has yet to be been determined. Recent reports showed that TNT increase the likelihood to achieve a conversion to surgery with high rates of R0 resection in borderline resectable (BR) and locally advanced (LA) PC patients. Stereotactic Body Radiation Therapy (SBRT) might be an intriguing component of TNT, but whether it burdens the