ESTRO 2021 Abstract Book

S1055

ESTRO 2021

(50-60Gy) and 2/7 centers favouring (C)RT indicated to treat no elective nodal areas in this situation. Conclusion We found a high rate of agreement between the centers and concordance with the recommendations of major guidelines at least for the main issues of work-up, treatment and follow-up. PET-CT, routine HIV testing and biopsies of suspicious LN seem underrepresented. The largest controversy regarding elective nodal target volumes concerns inclusion of the common iliac nodes. Doses to primary tumor, suspicious LN and elective nodal areas vary to some extent and are mainly in line with the recommendations, although sometimes above. OAR delineation, dose constraints, supportive care and treatment of early anal cancer are highly variable and represent areas for further standardization and research. PO-1278 Uterine Perforation During Image-Guided Adaptive Brachytherapy in Cervical Cancer Patients G. Yavas 1 , C. Yavas 1 , G. Inan 2 , M. Duzova 2 , O.V. Gul 2 , H. Basaran 2 1 Başkent University, Radiation Oncology, Ankara, Turkey; 2 Selcuk University, Radiation Oncology, Konya, Turkey Purpose or Objective In this study, we aimed to determine the incidence and clinical feature of uterine performance during our 3- dimensional image guided adaptive brachytherapy applications in patients with cervical cancer. Materials and Methods Between 2010-2020, 155 patients with the diagnosis of stage IB1-IVA cervical cancer were retrospectively evaluated. All the patients undergone 40 mg/m 2 cisplatin with concurrent external-beam radiotherapy (EBRT) to a dose of 50.4 Gy in 28 fractions, followed by intracavitary brachytherapy (BRT) 28 Gy in 4 fractions. BRT was performed using tandem-based intracavitary BRT with ovoids, using CT-based image-guided adaptive BRT method. Seventy-four (47.7%) patients had magnetic resonance imaging (MRI) just after EBRT prior to BRT application. Results Of the 155 patients, 9 (5.8%) had uterine perforation and among 620 applications 12 (1.9%) resulted in uterine perforation. The median age of the patient who had perforation was higher (63 years; range 44-84 years) than that of without perforation (52 years; range 29-85 years). The median tumor size was 5.4 for patients who had perforation, and 5.0 for the others. Five of the perforations were in retroverted uterine position (55.6%), and two of the perforations were in anteverted uterine position (22.2%), and one of the perforations was in retroflexed uterine position (11.1%). Pearson chi-square test showed that older age (p=0.026), larger tumors (0.024), and retroverted uterine position (p<0.001) were higher in patients who had perforation. Conclusion During CT-based adaptive BRT application, the larger tumor size, older age and retroverted uterine position may be risk factors for uterine perforation. Therefore prior to application all these parameters should be encountered and the application should be performed carefully in patients with these risk factors. PO-1279 68Gy EQD2 Constraint For G2-Vaginal Shortening In Post-Operative Endometrium. Preliminary Results. A. Rovirosa 1,2,3 , Y. Zhang 2 , G. Gomez 4 , C. Ascaso 2 , A. Herreros 1,2 , B. Fornes 1 , J. Rochera 1 , J. Mases 1 , A. Biete 1,2,3 , A. Torné 3 1 Hospital Clinic Universitari, Radiation Oncology, Barcelona, Spain; 2 Universitat de Barcelona, Fonaments Clinics, Barcelona, Spain; 3 Hospital Clinic Universitari, Gynecological Cancer Unit., Barcelona, Spain; 4 Hospital Angeles , Radiation Oncology, Chihuahua, Mexico Purpose or Objective Retrospective analysis in our centre in postoperative endometrial carcinoma (EC) has indicated a cut-off dose for G2 vaginal complications after vaginal-cuff brachytherapy (VBT). The present study aimed to evaluate the prospective preliminary results of the use of 68Gy EQD2 ( �� / �� =3Gy) as a dose limit at 2cm 3 of the most exposed volume of the vagina in order to reduce G2 late vaginal shortening in postoperative endometrial carcinoma (EC). Materials and Methods From November 2016 to October 2019, 69 postoperative EC patients underwent vaginal brachytherapy (VBT) +/- external beam radiotherapy (EBRT) and were prospectively analyzed. The median EBRT dose was 45Gy (range: 44Gy to 50.4Gy), 1.8-2Gy/day, 5 fractions/week. VBT was administered with the following schedule: 1 fraction of 7Gy after EBRT (34 patients) and 2 daily fractions of 7.5Gy in exclusive vaginal brachytherapy (35 patients). The dose was prescribed at 0.5 cm from the applicator surface with an active source length of 2.5 cm. The overall VBT dose was adjusted to meet the vaginal restriction of <68Gy EQD2 ( �� / �� =3Gy) at 2cm 3 of most exposed volume of the vagina. Late toxicity was prospectively assessed using RTOG scores for the bladder and rectum, and the objective criteria of LENT-SOMA for vagina. Statistics: descriptive analysis. Results With a median follow-up of 31.0 months, no vaginal-cuff recurrences were found. Late toxicity: Only 1 patient developed G1 rectal toxicity, while 21/69 patients (30.4%) and 3/69 patients (4.3%) developed G1 and G2 vaginal complications respectively. Only one (1.4%) of the 3 G2 late vaginal toxicities was manifested as vaginal shortening. Conclusion In postoperative EC patients treated with brachytherapy+/- EBRT, only one patient developed G2 vaginal shortening with the use of 68Gy EQD2 ( �� / �� =3Gy) as a dose constraint at 2 cm 3 of the most exposed volume of the vagina. These preliminary results confirm our previous retrospective studies on this dose constraint and show a much lower number of G2 vaginal shortenings in comparison to those of our reports without any dose Digital Poster: Gynaecological (endometrium, cervix, vagina, vulva)