Are 7.5Gyx2 fractions more efficient than 6Gyx3 in postoperative endometrial cancer brachytherapy?
PO-2140
Abstract
Are 7.5Gyx2 fractions more efficient than 6Gyx3 in postoperative endometrial cancer brachytherapy?
Authors: Faegheh Noorian1,2, Rosa Abellana2, Yaowen Zhang3, Antonio Herreros2,4, José Rochera5, Clara Baltrons4, Gabriela Antelo4, Aureli Torne6, Angeles Rovirosa4,2,7
1 Hospital clinic of Barcelona , Radiation Oncology Unit, Barcelona, Spain; 2University of Barcelona, Fonaments clinics Department, Barcelona, Spain; 3Henan provincial people’s hospital , cancer center, Zhengzhou, China; 4Hospital clinic of Barcelona, Radiation Oncology Unit, Barcelona, Spain; 5Hospital clinic of barcelona, Radiation oncology Unit, Barcelona, Spain; 6Hospital Clinic of Barcelona, Gynecological Cancer Unit, Barcelona, Spain; 7Hospital clinic of Barcelona, Gynecological Cancer Unit, Barcelona, Spain
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Purpose or Objective
To compare two vaginal brachytherapy (VBT) fractionation schedules in postoperative endometrial carcinoma (PEC) patients considering vaginal-cuff control, late toxicities (vagina, rectum, and bladder), EQD2(a/b=3) received in the most exposed 2cm3 to dose in clinical target volume (CTV) and vaginal dilator use.
Material and Methods
110 PEC patients were treated with two VBT schedules from 2011 to 2021. The 110 patients fulfilled the inclusion criteria for exclusive brachytherapy and were analyzed in two groups: Group-1 included 44 patients treated with 3 fractions of 6 Gy from September 2011 to April 2014 and Group-2 included 66 patients treated with 2 fractions of 7.5 Gy from July 2015 to November 2021. The dose was prescribed at 5mm from the applicator surface with an active length of 2.5cm. CTV was delineated in all the patients and the EQD2(a/b=3) received in the most exposed 2cm3 to dose in CTV was calculated. Late toxicity was prospectively assessed using RTOG scores for bladder and rectum, and the LENT-SOMA objective criteria for vagina. Statistics: Descriptive analysis, Chi-square and Student’s t tests.
Results
The median follow-up was 60 months (52.5-67.4) in Group-1 and 42.4 months (10.1-69.1) in Group-2. In the present study vaginal-cuff relapse and late toxicities in bladder and rectum were not found. 40 (39%) patients showed late vaginal toxicity: 21/44 (47.7%) patients in Group-1 (G1: 16 (36.4%), G2: 4 (10%), G3: 1 (2%)) and 19/66 (27.3%) patients in Group-2 (G1: 13 (18.2%) G2: 6 (9.1%)) (P=0.069). The mean EQD2(a/b=3) received by 2cm3 of the most exposed part of vagina was 63.7 Gy (SD±10.02) in Group-1 and 60.6 Gy (SD±3.90) in Group-2 (p= 0.066). Use of dilators > 9 months: 32 (72.7%) and 45 (68.2%) patients in Group 1 and 2, respectively (p=0.766). 12/44 (27.3%) patients in Group-1 and 21/66 (31.8%) in Group-2 used vaginal dilators (P= 0.766).
Conclusion
Despite the different fractionation schedules in PEC treatment, this is the first comparison of the present schedules. Considering the lack of vaginal relapses and the same vaginal toxicity rate in both groups, 2 fractions of 7.5 Gy seems more efficient in comparison to 3 fractions of 6 Gy in terms of patient comfort, work load and cost. However, further studies including more patients with a longer follow-up are required to confirm the present hypothesis.