ESTRO 2022 - Abstract Book

S490

Abstract book

ESTRO 2022

1 NCI, AIIMS-JHAJJAR, RADIATION ONCOLOGY, JHAJJAR, India; 2 NCI, AIIMS-JHAJJAR, Radiation Oncology, Jhajjar, India; 3 NCI, AIIMS-JHAJJAR, Medical Physics, Jhajjar, India; 4 NCI, AIIMS-JHAJJAR, Radiation oncology, Jhajjar, India Purpose or Objective Brachytherapy is the best conformal form of radiation delivery. We herein present High-dose rate (HDR) brachytherapy dosemetric and clinical outcomes performed during the covid pandemic. Materials and Methods Interstitial brachytherapy was performed in 19 patients head and neck carcinomas from May 2020 to August 2021. All patients were discussed in multidisciplinary tumor board. EBRT to elective neck was 45Gy in 20 fractions or 50/50,4 Gy in 25/28 fractions. Patients with positive lymph nodes were given SIB-IMRT of 56.26-58.25 Gy in 25 fractions (suspicious sub centimetric nodes) or 63 or 65 Gy in 28 fractions to the involved nodes (> 1cm). Double plane implant was performed in all patients (square or triangular geometry). Results Sixty-eight per cent were subjected to radical treatment, 16% to adjuvant and 16% were re-irradiated. Majority 68% of the patients were anterior tongue lesions, remaining included buccal mucosa (21%) and floor of mouth (11%) lesions. The median catheter placement was 8 catheters (range 5-9 catheters). Square implants were performed in 37% whereas remaining 63% were subjected to triangular implants. All patients in radical setting received a boost of either 24 Gy (85%) or 21 Gy (15%) in 8-7 fractions, 2 fractions a day at least 6 hours apart. Thirty-eight of these patients has lymph node involvement. In reirradiation setting brachytherapy alone was delivered in 42 Gy/12 fractions /6 days. In adjuvant setting brachy dose was 40-44 Gy in 10-11 fractions over 5/5.5 days. Median V 200 was 2.96cc (range 1.45-5.7cc), V150 median was 6.42cc (range 3.6-12cc) & V100 median was 25.5 cc (range 10-39.7cc). Median Dose non-uniformity ratio (DNR) was 0.26 (range 0.23-0.40). At a median follow of 35 days (range 0-465 days) all patients are disease free. No patient developed COVID infection before, during or after brachytherapy implant. Conclusion HDR brachytherapy is treatment option for head and neck carcinoma patients in radical, adjuvant and reirradiation setting. In the present study good dosemetric outcomes (median DNR of 0.26 and median V 200 of 3cc) were achieved. Longer follow up is required to confirm our findings as regards to efficacy and toxicity outcomes. 1 Centre Antoine Lacassagne, Department of radiation oncology, Nice, France; 2 Pôle Santé République, Department of radiation oncology, Clermont-Ferrand, France; 3 Centre Antoine Lacassagne, Department of radiation oncology, radiophysic, Nice, France; 4 Centre Antoine Lacassagne, Department of statistics, Nice, France Purpose or Objective Brachytherapy (BT) boost after radio-chemotherapy (RCT) is a standard of care in the management of locally advanced cervical cancer (LACC). As there is no consensus on high-dose-rate (HDR) BT fractionation schemes, our aim was to report the oncological outcome and toxicity profile of four different schemes using bi-fractionated HDR-BT. Materials and Methods This was an observational, retrospective, single institution study for patients with LACC receiving a HDR-BT boost. The latter was performed with a single implant and single imaging done on day 1. The different fractionation schemes were: 7Gy+4x3.5Gy (group 1); 7Gy+4x4.5Gy (group 2); 3x7Gy (group 3) and 3x8Gy (group 4). Summation of EBRT and BT doses was performed by calculation of EQD2. As HDR-BT fractionation evolved (number of fractions, dose per fraction, overall BT time), EQD2(t) was calculated taking into account the time factor for D 90 CTV HR and D 2cc of OARs for the different HDR-BT fractionation schemes. Local (LFS), nodal (NFS) and metastatic (MFS) recurrence-free survival as well as progression-free PD-0560 HDR brachytherapy boost for cervical cancer: 4 fractionation scheme efficacy and toxicity analysis M. Le Guyader 1 , D. Lam Cham Kee 2 , J. Hannoun-Levi 1 , M. Gautier 3 , M. Chand Fouche 1 , B. Thamphya 4