ESTRO 38 Abstract book

S776 ESTRO 38

preoperative (PO) radiation therapy (RT) in locally advanced oesophageal cancer patients. Material and Methods A total of 68 patients were treated with VMAT between 2014 and 2018 (DE 44% vs PO 56%). Dose prescription differed depending on the clinical scenario (54‐60 Gy in 30 fractions for DE treatments; 41.4/45 Gy in 23‐25 fractions in the PO setting). Most of the patients were given concurrent chemotherapy (CT). Two co‐planar and one non‐coplanar arcs were employed for VMAT delivery. Results Mean age was 71.6 years for the DE group and 64.7 for the PO one. Patients were mostly of male gender (DE 73.3%, PO 73.7%). The most represented histotype was squamous cell carcinoma (SCC)in both groups (76.7% vs 60.5%). Upper and middle thoracic esophageal location was more common in the DE group (76.7%), while in the PO group the mostly observed presentation was at the lower oesophagus and gastro‐oesophageal junction (60.6%). The most frequent clinical stage at diagnosis was T3 (83.3% vs 92.1%) and N1‐N2 (83.3% vs 86.9%) for the DE and PO groups, respectively. In the DE group, concurrent CT‐RT was administered to 76.7% of the patients. Up to 30% of patients in this group also underwent induction CT. In the PO group, all patients received concurrent CT‐RT. Treatment was globally well tolerated. Acute toxicity was generally mild. In patients treated with DE intent, ≥G3 toxicities were observed for oesophagitis (30%), anorexia (26.7%), fatigue (26.7%), nausea (6.7%) and vomiting (3.3%). In patients treated within a PO approach, ≥G3 anorexia (21%), oesophagitis (15.8%), fatigue (13.3%), nausea (5.3%) and vomiting (2.6%) were observed. Dosimetric results with respect to target coverage and normal tissue avoidance are presented in Table 1 .

(88.7%) patients presented recurrent disease. At the time of data analysis, 36 (67.9%) patients had died. At the univariate analysis, a high pre‐radiotherapy NLR was associated with reduced DFS (p=.039), but a significant association of an elevated NLR with OS was not detected (p=.110). Other prognostic factors identified were surgery (p<.001), tumor size ≥33m (p=.008), Ca 19.9 ≥107 (p=.025), radiotherapy (T+N vs T, p=.004). At the multivariate analysis, surgery remained the only prognostic factor for poor DFS (P=.005). In the subgroup of patients undergoing surgery, the multivariate analysis showed that elevated Ca 19.9 was the only significant prognostic factor for poor DFS (p=.021); high NLR resulted not statistically significant, but there was a trend toward significance (p=.060).

Conclusion High preradiotherapy‐NLR was correlated with poor DFS, but not with worst OS in patients with locally advanced pancreatic cancer undergoing radiotherapy. In patients undergoing surgery, Ca 19.9 had the most important prognostic role. EP-1428 Volumetric modulated arc therapy (VMAT) in the treatment of oesophageal cancer patients S. Martini 1 , G.C. Iorio 1 , F. Arcadipane 2 , P. Franco 1 , U. Ricardi 1 1 University of Turin, Department of Oncology- Radiation Oncology, Turin, Italy ; 2 Città della Salute e della Scienza, Department of Oncology- Radiation Oncology, Turin, Italy Purpose or Objective To evaluate feasibility, safety, toxicity profile, dosimetric results and early clinical outcomes of volumetric modulated arc therapy (VMAT) to deliver definitive (DE) or

Clinical outcomes are reported in Figure 1.