ESTRO 2021 Abstract Book

S1022

ESTRO 2021

Neoadjuvant chemoradiotherapy CROSS-protocol is the standard of care for locally advanced oesophageal cancer or oesophagogastric junctional cancer. Purpose The aim of this study was to demonstrate an improvement of complete pathological responses (ypCR) rates using Ryan scoring system on surgical specimens after a dose escalation neoadjuvant protocol compared to standard treatment. Secondary endpoints were disease-free survival (DFS) and acute gastrointestinal toxicity We prospectively evaluated patients with locally advanced oesophageal or oesophagogastric junctional adenocarcinoma (T1-T4, N0-N2, M0 according to the TNM classification, AJCC 8 th edition) who received neoadjuvant chemoradiotherapy. The radiation dose was 41,4Gy in 23 fractions or 50,4Gy in 28 fractions determined by a pilot study of dose-escalated radiation therapy with weekly administration of six cycles intravenous carboplatin AUC 2mg/mL and intravenous paclitaxel 50mg/m 2 ) followed by surgery. Results Between December 2015 and July 2020, 21 patients were treated according to the reported radiation schedules. Median age was 61 years (57-67). 95,2%(20) tumors were located at the esophagogastric junction and 4,8%(1) in medium esophagus. Stages of cancer were: 14,3%(3) stage IIA, 9,5%(2) stage IIB, 23,8%(5) stage IIIA and 52,4%(11) stage IIIB. 57,1%(12) patients received 41,4Gy in 23 fractions and 42,9%(9) received 50.4Gy in 28 fractions. ypCR were 41,67%(5) and 55,6%(5) in the 41,4Gy and 50,4Gy subgropups respectively (Fisher´s test p=0.67). After a median follow-up of 8 months (3-15), DFS in the 41,4Gy subgroup was 13,73 months (95%CI, 8,43-19,04) and 36,6 months (95%CI, 17,82-55,38) in the 50,4Gy subgroup (Long Rank, Mantel-Cox 5,184,p=0,226). Grade III acute gastrointestinal toxicity was 16%(2) and 33,33%(3) in the 41,4Gy and 50,4Gy subgroup respectively, (Pearson´s test ,p=0,552) with 11,1%(1) grade IV toxicity in the 50,4Gy subgroup. Conclusion There is a trend of higher complete pathological responses and disease-free survival in the 50,4Gy subgroup with an acceptable gastrointestinal toxicity. We need well-designed randomized and controlled trials to obtain conclusive data. PO-1238 Volumetric modulated arc therapy is superior to intensity modulated radiotherapy for liver sparing in stereotactic body radiotherapy for hepatocellular carcinoma Y. Kundel 1 , Y. Korzets 2 , M. Weinstock-Sabbah 3 , A. Moor 4 , N. Gordon 5 , D. Bragilovski 4 , S. Stemmer 6 , A. Popovtzer 3 , B. Brenner 3 , E. Fenig 3 , A. Allen 3 1 Rabin medical center, Davidoff cancer center, Pethach tikva, Israel; 2 rabin medical center, Davidoff cancer center, Pethach tikva, Israel; 3 Rabin medical center, Davidoff cancer center, Petach tikva, Israel; 4 Rabin Medical Center , Davidoff Cancer Center, Pethach tikva, Israel; 5 Davidoff Cancer Center, Davidoff Cancer Center, Rabin Medical Center , Pethach tikva, Israel; 6 Rabin Medical Center , Davidoff Cancer Center, Petach tikva, Israel Purpose or Objective The best radiotherapy delivery modality of stereotactic body radiotherapy for hepatocellular carcinoma is a matter of debate. The purpose of this retrospective study was to compare planning parameters with volumetric modulated arc therapy to static intensity modulated radiotherapy in treatment of hepatocellular carcinoma treated with stereotactic body radiotherapy Materials and Methods Twenty patients with localized hepatocellular carcinoma who were treated with stereotactic body radiotherapy were re-planned using two different radiation techniques: intensity modulated radiotherapy and volumetric modulated arc therapy. Patients with Child A cirrhosis received 45-54 Gy in 3 fractions and 5 patients with Child B cirrhosis received 30 Gy in 5 fractions. Planning was optimized to minimize doses to organs at risk without compromising coverage of the planning treatment volume. Volumetric modulated arc therapy and intensity modulated radiotherapy plans were compared using the conformity and homogeneity indices of the planning treatment volume, monitor units for time of treatment delivery, and other dose volume histogram metrics Results The conformity index of volumetric modulated arc therapy plans were superior to those of intensity modulated radiotherapy (1.11±0.05 vs 1.18±0.06 (p <0.05). The monitor units were significantly lower for volumetric modulated arc therapy (423.78±50.65) than for intensity modulated radiotherapy (890±160.68) (p <0.01). Stomach max dose, normal liver V15 Gy, normal liver mean dose were also decreased with volumetric modulated arc therapy planning. This was achieved without increased :V30 Gy of duodenum and small bowel, 10 cc (Gy) of duodenum, mean dose of right kidney and cord max dose Conclusion To conclude, planning treatment volume coverage was more conformal with volumetric modulated arc therapy planning, with lower monitor units and shorter delivery time compared to intensity modulated radiotherapy in all patients. Moreover volumetric modulated arc therapy planning was more effective than intensity modulated radiotherapy planning in the sparing of normal liver and stomach. according to CTCAE V.4. Materials and Methods PO-1239 99mTc-macroaggregated albumin SPECT/CT in HCC treated with Selective Internal Radiation Therapy E. Lodi Rizzini 1 , V. Laghi 1,6 , L. Cavallini 1,6 , E. Deraco 1,6 , D. Vallerossa 1,6 , C. Scampoli 1,6 , C. Bellarosa 1,6 , S. Cammelli 1,6 , S. Strolin 2 , L. Strigari 1 , R. Golfieri 3,6 , S. Fanti 4,6 , G.P. Frezza 5 , A.G. Morganti 1,6 , F. Monari 1 1 Radiation Oncology, IRCSS Azienda Ospedaliero-Universitaria di Bologna, Bologna, Italy; 2 Medical Physics, IRCSS Azienda Ospedaliero-Universitaria di Bologna, Bologna, Italy; 3 Radiology Unit, IRCSS Azienda Ospedaliero-Universitaria di Bologna, Bologna, Italy; 4 Nuclear Medicine Center, IRCSS Azienda Ospedaliero- Universitaria di Bologna, Bologna, Italy; 5 Radiotherapy Department, Ospedale Bellaria, Bologna, Italy;