ESTRO 2020 Abstract Book

S558 ESTRO 2020

Conclusion SBRT following induction chemotherapy is a safe option in the context of a TNT approach for BRPC and LAPC. The rate of negative margins is promising, especially in the setting of complex long-course downstaging and challenging indication to surgery. PO-1049 Biliary tract tumors: the role of chemoradiotherapy – a review of the last 10 years M. Simas 1 , S. Saraiva 1 , V. Mareco 2 , M. Abdulrheman 1 , M.F. Pina 2 1 Centro Hospitalar Universitário Lisboa Norte- E.P.E., Serviço de Radioterapia, Lisbon, Portugal ; 2 Centro Hospitalar Universitário Lisboa Norte- E.P.E., Serviço de Radioterapia, Lisboa, Portugal Purpose or Objective Biliary tract tumors (BTT) are relatively rare and particularly aggressive, with low survival rates. External beam radiotherapy (EBRT) and chemotherapy (CTX) are important components of adjuvant and definitive treatments for locally advanced BTT. Emerging imaging techniques of EBRT ( e.g. , image-guided [IGRT] and 3D- conformal [3DC] dose administration) can translate into better cancer outcomes. The aim of this study is to assess the impact of EBRT, concomitant with CTX, on the overall (OS) and progression-free survivals (PFS) of patients (pts) with BTT treated at the Centro Hospitalar Lisboa Norte. Material and Methods An observational, longitudinal and retrospective analysis was performed on 114 pts with BTT who were treated at the Radiotherapy Department between February 2009 and August 2019. Forty-three pts underwent 3DC-EBRT adjuvant to surgery ( n = 37; 86%) or radical ( n = 6; 14%). Median total dose: 50.4 Gy (range: 30 - 59.5). Median fractionation: 1.8 Gy/fraction (range: 1.8 - 3). Forty-one pts (95.3%) underwent concomitant CTX: capecitabine (23.3%), gemcitabine (GC) (18.6%), 5-fluorouracil (5FU) (9.3%), GC + 5FU (4.7%), other schemes (9.3%), not available (NA) (34.9%). Median age at diagnosis: 65 years old. Male: 31 pts (72.1%); female: 12 pts (27.9%). Tumor location: ampulla of Vater (AV) – 25.6%; distal – 37.2%; Klatskin tumor (KT) – 23.3%; gallbladder – 7%; intrahepatic – 7%. Tumor stage: I – 7%; II – 39.5%; III – 27.9%; IV – 16.3%; NA – 9.3%. Differentiation grade (DG): well (G1) – 35.7%; moderately (G2) – 39.3%; poorly differentiated (G3) – 25%. Results Median OS: 49.6 months (mos). OS at 6 mos and 1, 2, 3 and 5 years: 94.7%, 86.8%, 67%, 35% and 17.5%, respectively. Median OS according to BTT location: AV – 68.3 mos; distal – 36.4 mos; intrahepatic – 30 mos; gallbladder – 27.7 mos; KT – 22.3 mos. Median OS according to DG: G1 – 44.2 mos; G2 – 27.6 mos; G3 – 23.4 mos. Pts with AV-localized BTT had significantly longer OS compared to other locations ( p = 0.04). Median PFS: 26.7 mos. PFS at 6 mos and 1, 2, 3 and 5 years: 91.3%, 73.9%, 26.2%, 17.4% and 8.7%, respectively. Median PFS according to BTT location: AV – 43.5 mos; distal – 28.7 mos; KT – 18.6 mos; gallbladder – 6.5 mos. Pts with gallbladder-localized BTT had significantly lower PFS compared to other locations ( p = 0.04). There were no statistically significant differences in OS and PFS stratified by DG, stage or CTX scheme. Conclusion This case series shows good survival results for BTT treated with chemoradiotherapy in adjuvant or radical context, particularly those in the ampulla of Vater. These results should be complemented with studies of greater statistical power.

postoperative course is unclear. This study aims to investigate the effects of SBRT on postoperative course and margins status within a setting of TNT. Material and Methods Patients suffering from BRPC and LAPC undergoing induction chemotherapy and preoperative SBRT, and candidates to surgical exploration in a national referral Center from November 2016 to July 2019 were considered as eligible. SBRT was delivered over 5 consecutive daily fractions prescribing 30 Gy to the Planning Target Volume (PTV) tumor with a simultaneous integrated boost (SIB) of 50 Gy to the tumor-vessel interface (TVI). The dose was reduced to 25 Gy on the overlap area between the PTV and the Planning Organs at Risk Volume. R0 resection was defined as the absence of microscopic tumor invasion within 1 mm of resection margins, assessed by axial slicing of the surgical specimen. Postoperative complications were defined according to the International Study Group of Pancreatic Surgery (ISGPS) classifications, and the burden of complications was assessed through the Clavien- Dindo Classification (CDC). Results The study population consisted of 72 patients. Overall, 61 patients (84.7%) underwent major pancreatic resections, while 11 patients (15.3%) underwent explorative laparotomy (intraoperative finding of LA unrecostructible tumors in 2 cases [3.2%], and distant metastasis in 9 cases [14.7%]). Vascular resection was required in 30 patients (49.2%), with 5 patients (8.2%) undergoing distal pancreatectomy with celiac axis resection (DP-CAR). R0 resection was achieved in 36 patients (59%) and in 3 cases (4.9%) a complete pathologic response was found at final pathology (ypT0N0R0). Postoperative overall morbidity was 51.4% and 2 patients died within 90 days (90-day mortality 2.8%). Post-operative Pancreatic Fistula occurred in 4 patients (5.6%) while post-pancreatectomy hemorrhage was detected in 5 patients (6.9%), with 3 patients (4.9%) needing re-intervention. Severe complications (CDC ≥ III) were reported in 19.4% of patients