ESTRO 2023 - Abstract Book

S1945

Digital Posters

ESTRO 2023

and VIa representing 38% and 8% respectively.

For external radiotherapy, the three dimensional (3D) conformal radiation therapy was used in all patients. Regarding the dose, 92% of the patients had received 46 Gray (Gy) in 23 fractions. Concomitant chemotherapy was based on cisplatin in 93.6% of cases with an average of 5 weekly cycles. For brachytherapy, the schedule of 4 sessions of 7 Gy was used in 88.88% of our patients. The spread of the whole treatment on average is 59 days. Analysis of the dose-volume histograms (DVH) showed that 2cc of the bladder and 2cc of the rectum had received 91.2 Gy and 78Gy respectively, the bladder constraint was respected in 74.6% of the patients and the rectum constraint was respected in 53.9% of patients. For the coverage of target volumes, D90 of high-risk clinical target volume (HR-CTV) and D90 of Intermediate Risk clinical target volume (IR-CTV) were respectively 79.7 Gy and 67.75 Gy in EQD2, the objectives were achieved in 77% of patients. Concerning the tolerance of radiotherapy, acute toxicities were dominated by enteritis and cystitis which presented respectively 41% (67.5% of grade II) and 29.5% (78% of grade II), no grade IV toxicity was detected. For chronic toxicities, the most common were radiation proctitis, cystitis and vaginal synechia found in 63% (65% grade II), 27% (71% grade II) and 27% (76% grade II) cases respectively. After an average follow-up of 38 months, relapses are around 9.5%, including 7.9% of local recurrences. Conclusion By comparing our results with those of the literature, we noted more toxicities in our patients, in particular radiation proctitis, this can be explained by the overestimation of volumes with the CT imaging, the use of the 3D conformal radiation therapy and the frequency of locally advanced stages. On the other hand, the LC rate agrees with the data in the literature. 1 Faculty of medicine, university of Oran 1, Algeria., Department of radiotherapy, EHSO Emir Abdelkader of Oran, Oran, Algeria; 2 Faculty of medicine, university of Oran 1, Algeria., Department of radiotherapy, EHSO Emir Abdelkader of Oran, oran, Algeria; 3 Faculty of medicine, university of Oran 1, Algeria, Department of radiotherapy, EHSO Emir Abdelkader of Oran, oran, Algeria Purpose or Objective Brachytherapy plays a fundamental role in the therapeutic approach of patients with cervical carcinoma. Technical modalities have evolved during the last decades: stepping source technology, imaging modalities development, treatment planning system integrating 3D images. The aim of this retrospective study was to assess the impact of radiotherapy with dose escalation by utero-vaginal brachytherapy in HDR at more than 80 Gy in EQD2. Materials and Methods Between 2014 and 2020, 68 patients with locally advanced cervical cancer were treated with chemo-radiotherapy followed by a boost by three-dimensional utero-vaginal brachytherapy at high dose rate with dose escalation greater than 80Gy in EQD2 ( α / β =10) according to GEC-ESTRO recommendations. Results The median follow-up is 37.45 monthS, the average age of the patients is 56.2 years, the squamous histological type is found on 90% of cases. The FIGO IIB stage is the majority in 87% of cases, and the average tumour is 41.59mm. The average dose of D90 HRCTV in association with the external radiotherapy in EQD2 ( α / β =10) was between 80 and 85Gy in 75% of cases, between 86 and 90Gy in 20.6% of cases, and in only one case (1.5%) greater than 90Gy. The rate of tumour control was 95.6%. The probability of survival without recurrence at 5 years is 94.9% ± 2.9. Eight patients suffered from late urinary and digestive toxicity greater than grade 2 (five digestive toxicity and three urinary toxicity grade 3). Conclusion Radio-chemotherapy followed by utero-vaginal brachytherapy with dose escalation in the treatment of locally advanced cervical cancer providing high local control rates with acceptable toxicity. PO-2162 Dose escalation in brachytherapy for locally advanced cervical cancer M. benarbia 1 , L. taleb 2 , H. boumedien 3 , A. boukerche 3

Poster (Digital): Brachytherapy: Physics

PO-2163 The effect of eccentric plaque placement on tumour dose in Ruthenium plaque brachytherapy

J.P.M. Flanagan 1,6 , W.H.F. Udovenya 2 , M.A. Astrahan 3 , D. McKay 4 , C. Phillips 5 , J.D. McKenzie 4 , R. O'Day 6,4 , L.S. Fog 4,7

1 University of Melbourne, Ophthalmology, Department of Surgery, Melbourne, Victoria , Australia; 2 University of Melbourne, Ophthalmology, Department of Surgery, Melbourne, Victoria, Australia; 3 Keck School of Medicine, University of Southern California, Department of Radiation Oncology, Los Angeles, California, USA; 4 Royal Victorian Eye and Ear Hospital, Department of Ocular Oncology, Melbourne, Victoria, Australia; 5 Peter MacCallum Cancer Centre, Department of Radiation Oncology, Melbourne, Victoria, Australia; 6 Centre for Eye Research Australia, Ocular Oncology Research Unit, Melbourne, Victoria, Australia; 7 The Alfred Hospital, Alfred Health Radiation Oncology, Melbourne, Australia

Purpose or Objective