ESTRO 2022 - Abstract Book

S1088

Abstract book

ESTRO 2022

Materials and Methods Twenty patients of carcinoma oesophagus, planned for radical intent RT, were positioned using thoracic wing board device and planning CECT scans were acquired in free-breathing (FB) and 4 Dimensional CT (4DCT) using Varian Real-time Position Management (RPM) system. Patients were subdivided into Grp1: upper ± middle third (12 patients), and Grp2: lower third ± gastro-esophageal junction (GEJ) involvement (8 patients). Contouring was done on FB and 10 phases of 4DCT to generate ITV for motion assessment. Motion was assessed in superio-inferior (SI), anterio-posterior (AP) and medio-lateral (ML) directions manually using 1.0 mm grid and GTV of free-breathing scan as reference for determination of internal margin (IM). During treatment, verification MV Portal Imaging (PI) & KV Cone Beam CT (CBCT) were acquired on alternate days, with a minimum of three images in the first week and weekly thereafter. Off-line matching was done using carina and vertebral bodies as surrogates for PI while for CBCT, bone auto-match using clip box for vertebral bodies was used. Setup margins (SM) were calculated using van Herk’s formula (2.5 Σ + 0.7 σ ) for PI and CBCT. PTV margins were calculated using SM+IM in all directions. Results For tumor motion assessment, 20 patients with 200 image sets corresponding to phases of respiration were assessed using 4DCT data. Internal Margins, mean ± SD (mm) in SI, AP, and ML directions for Grp1 were 4 ± 2, 2 ± 1, and 2 ± 1 while for Grp2 were 6 ± 2, 3 ± 1, and 3 ± 2 respectively. 20 patients with 164 Portal images and 112 CBCT images were assessed for set-up errors. The setup margins in SI (Y), AP (Z), and ML (X) axes for all the 20 patients were from PI were 13mm, 7mm, and 12mm respectively, and from CBCT’s were 11mm, 5mm, and 9mm respectively. The PTV margins (IM+SM) using PI for Grp1 were 17mm, 9mm, and 14mm and for Grp2 were 19mm, 10mm, and 15mm in SI, AP, and ML directions respectively. Whereas PTV margins using CBCT as verification modality for Grp1 were 15mm, 7mm, and 11mm, and for Grp2 were 17mm, 8mm, and 12mm in SI, AP, and ML directions respectively. Conclusion Both setup errors and motion were maximal in the SI direction and for lower 1/3rd ±GEJ tumors. CBCT verification can further lead to reduction in PTV margins. 1 Dr. Ram Manohar Lohia institute of medical sciences, Radiation Oncology, Lucknow, India; 2 Dr. Ram Manohar Lohia institute of medical sciences, Radiation oncology, Lucknow , India; 3 Dr. Ram Manohar Lohia institute of medical sciences , Radiation Oncology , Lucknow, India; 4 Dr. Ram Manohar Lohia institute of medical sciences , Radiation Oncology , Lucknow , India Purpose or Objective Although neoadjuvant chemoradiotherapy (CTRT) followed by surgery is preferred, definitive CTRT is also one of the recommended management strategies for squamous cell carcinoma of middle oesophagus (ME-SCC). Definitive CTRT protocols are evolving. We aimed to prospectively evaluate the acute toxicity and early clinical outcome in ME-SCC treated with definitive CTRT using volumetric modulated arc therapy (VMAT) with simultaneous integrated boost (SIB). Materials and Methods We enrolled 15 patients of histologically proven ME-SCC in a prospective interventional study (IEC 54/19) between December 2019 to December 2020. 60 Gray at 2 Gray per fraction was delivered to the gross disease and elective nodes were irradiated to 48 Gray at 1.6 Gray per fraction, 5 fractions per week with SIB-VMAT. Concurrent cisplatin 75mg/m 2 (on day 1 and day 21) and 5-Fluorouracil 1000 mg/m 2 (day 1 to 4 and day 21 to 25) were delivered. Acute toxicities are reported with Common Terminology Criteria for Adverse Events (CTCAE) version 5.0. Results Median age was 52 years (32- 68 years) and 60% were female. Median Karnofsky performance scale was 80. Stage distribution was II:III in 9:6 patients respectively. 13 patients (86.6%) completed CTRT as per protocol. Due to treatment related toxicity, one patient received 50Gy with 2 cycles of concurrent chemotherapy and one patient succumbed after 5 fractions of radiotherapy due to unknown reason. Median V 95 for planning target volume (PTV) for primary and elective nodes was 98.42±1.48% and 99.43±0.82% respectively. Median mean dose received by both lungs was 18.64±2.81 and median lung volume receiving 20Gy (V 20 ) was 33.16±5.23% of the total lung volume. Median D max of cord and median mean dose to heart were 42.5±1.15Gy and 27.17±6.05Gy respectively. Median follow-up was 13 months (5-19 months). 10 (67%) patients had complete response till the time of last follow-up, 1 patient had recurrence of disease after six months of completion of treatment, 3 patients had residual disease at the time of first follow-up. Acute toxicity profiles observed were grade 3 in 3 patients (20%), grade 4 (dysphagia) in 1 patient (6.6%). None had grade 5 toxicity. The highest grade of various Grade 1-3 toxicities assessed are enumerated in Table 1. At the end of 3 months only 1 patient with no radiological evidence of disease, had grade 3 dysphagia. PO-1291 Acute toxicity and clinical outcome in carcinoma middle oesophagus treated with definitive CTRT S. Jalota 1 , R. Khurana 2 , A.K. Gandhi 1 , M. Rastogi 3 , R. Hadi 4 , S.P. Mishra 4 , A.K. Srivastava 3 , A. Bharati 3

Toxicity

Grade 1 Grade 2 Grade 3 4 (26.6%) 2 (13.3%) 1 (6.6%) 5 (33.3%) 7 (46.6%) 2 (13.3%)

Haematological

Dysphagia Esophagitis Pneumonitis

10 (66.6%) 5 (33.3%) 0 5 (33.3%) 4 (26.6%) 0