ESTRO 2021 Abstract Book

S1059

ESTRO 2021

PO-1285 Postoperative high dose rate brachytherapy in endometrial cancer: three versus six fractions. L. Cardoso 1 , L. Gómez 1 , P. Alonso 1 , S. Pena 2 , M. Herrera 1 , P. Valencia 1 , A. Casado 1 , M. Martín 2 , I. Solis 1 , M. Iglesias 3 , D. Rodríguez 1 , M.D.C. Salas 4 , M.L. Del Valle 1 , Á. Del Castillo 2 , J.F. Gutiérrez 1 , M. Sánchez 1 , P. Diezhandino 1 1 Hospital Clínico Universitario de Valladolid, Radiation Oncology, Valladolid, Spain; 2 Hospital Clínico Universitario de Valladolid, Medical Physics, Valladolid, Spain; 3 Centro Oncológico de Galicia, Radiation Oncology, A Coruña, Spain; 4 Hospital Universitario Puerta del Mar , Radiation Oncology, Cádiz, Spain Purpose or Objective To analyze the impact of two different fractionation regimens of endovaginal HDR brachytherapy in women intervened for endometrial cancer. We analyzed local recurrence, locorregional failure and acute and late rectal, vaginal and bladder toxicity. Materials and Methods We carried out a longitudinal and retrospective analytical study of a historical cohort. All patients were intervened of endometrial adenocarcinoma GI or GII, with IA and IIB stage, treated with endovaginal HDR brachytherapy exclusively, at the Hospital Universitario Puerta del Mar in Cádiz between 2008-2013. The entire cohort was stratified into two groups, one of these groups received three fractions of 7 Gy with high dose brachytherapy (the study group) and the other one was treated with six fractions of 4-4,5 Gy of HDR brachyterapy (the control group). The average follow-up is 47.9 months with a median of 48 months. The standard deviation is 11.59 months showing a minimum and a maximum of 20 and 72 months respectively. Results We have not observed local recurrence after treatment in any group. In fact, only 5 patients presented loco regional recurrence, 1 case in control group and 5 cases in the study group, with a p value = 0,281, which demonstrated not significant difference. Significants differences about acute toxicity of rectum, bladder or vagina as well as chronic toxicity at the vaginal or rectal level were not found. Althought, there were differences about cronic bladder toxicity. According to RTOG scale, we have detected 50% G1 toxicity in control group, compared to 12.5% in the 3- fraction scheme, both evaluated with a minimum follow-up of 20 months and a median of 48 months.

CONTROL GROUP (N = 30)

STUDY GROUP (N= 40)

VARIABLE

P VALUE*

Local relapse

0

0

1

Locorregional failure

3,3%

10%

0,281

Acutte bladder toxicity 13,3%

7,5%

0,452

Acutte vaginal toxicity 100%

95%

0,503

Acutte rectal toxicity 0%

5%

0,503

Late bladder toxicity

50%

12,5%

0,001

Late vaginal toxicity

36,7%

40%

0,809

Late rectal toxicity 1 * Calculated using Fisher's exact test or Chi square test based on the data. 0% 2,5%

Conclusion According to the results, it may be confirmed that the hipofractionated BT scheme is safe and reduces the bladder late toxicity. We confirm that there would be no relevant differences of local and loco regional relapse; acute vaginal, bladder and rectal toxicity; and finally, late vaginal and rectal toxicity.

PO-1286 Prognostic factors for non-endometrioid carcinoma J.A. Domínguez Rullán 1 , T. Muñoz Miguelañez 1 , M. Martín Sánchez 1 , S. Sancho García 1 1 Hospital Universitario Ramón y Cajal, Radiation Oncology, Madrid, Spain

Purpose or Objective To report the outcome and treatment approach of patients diagnosed with localized or locally advanced non- endometrial carcinoma treated with curative intent and identification of prognostic factors. Materials and Methods From 2004 to 2016, 56 patients were treated in our institution with curative intent. Data were compared by X2 test and Fisher’s exact test. Overall survival (OS), cancer-specific survival (CSS) and progression-free survival (PFS) were calculated using the Kaplan-Meier. Cox-regression analysis was used to assess possible prognostic factors like age, clinical stage, histological subtype, tumor size, lymphovascular invasion (LVSI), peritoneal- cytology and adjuvant treatment. Results Mean age at diagnosis was 69 years (range 48-90). There were 20 patients stage IA, 9 stage IB, 11 stage II and 16 stage III. Twenty-six patients (46.4%) were papillary-serous carcinoma (UPSC), fifteen (26.8%) clear-cell carcinoma (CCC), thirteen (23.2%) uterine-carcinosarcoma (UCS) and two undifferentiated carcinoma. All patients underwent radical hysterectomy with double anexectomy and lymph node dissection was done in 71.4% of cases. Adjuvant radiotherapy was performed in 85.7%: 21.4% vaginal cuff brachytherapy (VCB) and 64.3% external beam radiation therapy (EBRT) + VBT. Adjuvant chemotherapy (CT) was indicated in 58.9% of patients. Median follow-up was 39 months. 2 and 5-year OS were 86.9% and 66.8%; CSS 88.5% and 70.4%; and PFS 74.9% and 59.6%, respectively. Vaginal recurrence was seen in 5.4% of cases, nodal recurrence in 14.4% and distant metastasis in 32.1%. In multivariable analysis age, positive LVI, positive peritoneal cytology and