ESTRO 2021 Abstract Book

S1035

ESTRO 2021

1 Amrita Institute of Medical Sciences, Radiation Oncology, Cochin, India; 2 Amrita Institute of Medical sciences, Radiation Oncology, Cochin, India

Purpose or Objective Long course conventional radiation therapy with concurrent chemotherapy is among the most commonly practiced neoadjuvant therapy schedules for rectal carcinoma.This prospective study aims to evaluate the safety , response rates and quality of life (QOL) using a novel moderately hypofractionated schedule with concurrent chemotherapy. Materials and Methods All patients between age group of 18 to 75 years diagnosed with locally advanced adenocarcinoma rectum T3, T4 disease or node positive disease were included in this study after an informed consent. Patients received radiation therapy to a dose of 45Gy in 20 fractions (2.25Gy per fraction, over 4 weeks) with IGRT (Helical Tomotherapy) technique along with concurrent oral Capecitabine (825mg/m 2 / dose, twice daily). Toxicity assessment was done using CTCEA Version 5.0 and Quality of Life (QOL) assessment was done using FACT-C questionnaire at various time points. The pathological response was graded using Modified Ryan tumour regression grading score. Results A total of 25 patients were included in this prospective study, among whom 13(52%) were mid rectal tumours and 9 (36%) low rectal tumours. 16 patients (64%) had circumferential resection margin (CRM) involved or threatened disease. Only one patient has a grade 3 acute adverse event (skin toxicity), while all others experienced only Grade 1-2 toxicities. Median interval to surgery after completion of chemoradiation therapy was 8.4 weeks (range: 5.2 – 10.7 weeks). Pathological response evaluation revealed that 7 patients (28%) had a pathological complete response (pCR),2 patients (8%) - TRG score 1; 14 (56%) TRG2 and 2 (8%) TRG 3. 23 patients (92%) had a CRM negative resection, while 2 patients (8%) were noted to have focal margin positivity at CRM. FACT C and FACT-TOI (Trial outcome index) scores show a statistically significant improvement in quality of life of patients in this study cohort from baseline to 3 months after radiation therapy. Conclusion Moderate hypofractionated radiation therapy along with concurrent chemotherapy is safe and achieves good response rates . IGRT in rectal cancers could be a promising tool for intensification of treatment and improving tumour regression. PO-1256 Local excision followed by radiotherapy or chemoradiotherapy for early stage rectal adenocarcinoma. S. Santana Jimenez 1 , J. Romero Fernández 1 , M. Hernández Miguel 2 , A. Sánchez Movilla 3 , I. Alonso Sebastián 3 , R. Benlloch Rodríguez 1 , S. Córdoba Largo 1 , J.F. Obeso Herrera 1 , A. Herreros de Tejada 4 , J. Santiago García 4 , M. López Valcarcel 1 , B. Gil Haro 1 , P. Sarrión Rubio de La Torre 1 , L. Paisán Palacio 5 1 Puerta de Hierro University Hospital, Radiation Oncology, Madrid, Spain; 2 Puerta de Hierro University Hospital, Radiation Oncology, Madrid, Spain; 3 Puerta de Hierro University Hospital, Surgery, Madrid, Spain; 4 Puerta de Hierro University Hospital, Gastroenterology, Madrid, Spain; 5 Puerta de Hierro University Oncology, Radiation Oncology, Madrid, Spain Purpose or Objective Local excision followed by adjuvant radiotherapy or chemoradiotherapy in early-stage rectal cancer is an alternative for TME (total mesorectal excision) in selected patients. The objectives are to evaluate overall (OS), disease-free (DFS), local relapse-free (LRFS), nodal relapse-free (NRFS) and distant metastases-free (DMFS) survivals; and evaluation of prognostic factors and toxicity. Materials and Methods Between 2004 and 2020, 24 patients (p) with anatomopathological diagnosis of rectal adenocarcinoma and clinical stage cT1-2cN0M0 were treated in our institution. Clinical characteristics: 13 males (54%); 11 females (44%). Mean age 68 yo (44-91). Clinical stage: cT1: 13p (54%), cT2: 11p (44%). Treatment: surgery consisting in TAMIS (Transanal minimally invasive surgery) in 20 patients (84%) and DSE (endoscopic submucosal disease) in 4 patients (16%). All of patients received adjuvant pelvic irradiation +/- boost in surgical anastomosis with total mean dose of 46 Gy (45-56). Eighteen of 24 patients received concomitant capecitabine (825 mg/m2/12 x 28 days). Statistics test: student´s t test, ANOVA, chi square, Kaplan meier and log Rank test. Results The median follow-up was 42 months (0-165). Local recurrence in 5 patients (21%), lymph node recurrence in 2 patients (8%) and distant metastasis in 4 patients (17%). Four patients died (17%). Five-year OS, DFS, LRFS, NRFS and DMFS were 68%, 63%, 69%, 78% and 68% respectively. A better 5-y LRFS was observed in patients with pT1 (78% vs 42% for pT2-3; p=0.038). A worse 5-y NRFS was observed in patients with pT3 (0% vs 80% and 100% for pT1 and pT2, respectively; p < 0.001) and R1 resection margin (67% vs 83% for R0; p=0.025). Patients with microscopically affected surgical margin (R1) has a worse 5-y DMFS (0% vs 94% for R0; p=0.029). Adverse prognostic factors for overall survival were pT3 (5-y OS of 0% vs 75% and 67% for pT1 and pT2, respectively; p=0.052) and resection margin (5-y OS of 0% vs 84% for R1 and R0, respectively; p=0.023). Of 20 evaluable patients, CTCAEv5 grade 1-2 toxicities were diarrhea (18 patients, 72%), proctitis (17 patients, 68%), rectal mucositis ( 16 patients, 64%), rectal pain (11 patients 44%), fecal incontinence (7 patients, 28%), cystitis (13 patients, 52%), fatigue (4 patients, 16%), dermatitis radiation (20 patients, 80%). Only one grade 3 diarrhea was described. Hematological toxicity grade 1-2 was anemia (2 patients, 8%), thrombopenia (2 patients, 8%), leucopenia (1 patient, 4%), neutropenia (1 patient, 4%).