ESTRO 2024 - Abstract Book

S222

Brachytherapy - Gynaecology

ESTRO 2024

Cervical cancer is the fourth most common malignancy in women and also the fourth most common cause of death from cancer in women worldwide [1].For locally advanced diseases, concomitant Cisplatin-based chemo radiation is considered the standard of care with brachytherapy(BT) boost to the residual disease[2-4].BT improves clinical outcome and is a vital component of the curative treatment of locally advanced disease. High dose rate (HDR) BT is the most commonly utilized technique for BT boost delivered with intra-cavitary applicator and if needed with an added interstitial component. It consists of multiple applications employing high dose delivered over short time in each fraction. This fractionated schedule at times lead to protracted overall treatment time (OTT) which is detrimental in terms of oncological outcomes[5]. The delivery of two fractions of RT in single application of HDR-BT may lead to shortening of OTT and would be cost effective as it will obviate need for applicator insertion for all fractions separately. The purpose of this study was to evaluate the early efficacy and toxicity of treatment with two fractions per application in HDR-BT in locally advanced cervical cancer. The present study is retrospective in design. The data of patients of cervical cancer treated with curative intent and received two-fractions in each HDR –BT application between2019-2022 were retrieved and analyzed. Patients received 45-50.4Gy in External beam RT (EBRT) followed by HDR-BT. The BT planning was done on CT data set with intracavitary/interstitial applicator and dose was prescribed at Point A. The dose per fraction was 7Gy and two applications were done 1-week apart. The Organ-at-risk (OAR), i.e., bladder, rectum, and sigmoid, were contoured in both applications. The planning constraints were D2cc rectum , 75Gy, D2cc sigmoid, 75Gy, and D2cc bladder,90Gy (includes both EBRT and BT)[6,7].All the patients received two fractions in single BT application that were delivered at a minimum interval of six hours. Plans were optimized whenever required. Post treatment follow-up was performed 3-monthly for first two years. A total of 45 patients were identified and analyzed for their patient, tumor characteristics along with their treatment-related toxicities and outcomes. The median age of the patients was 52 years, most of them were aged over 50 (59%). Majority presented with negative lymph nodal status (74.4%), had primary tumor sizes >4cm (79.5%), squamous cell carcinoma (87.2%), and FIGO Stage II disease (56.4%). Patients received EBRT with 45Gy in 25 fractions being employed as the most common fractionation schedule (75.5%). The majority of the patients underwent intra-cavitary brachytherapy (88.8%) while the rest received interstitial brachytherapy. BT fractionation scheme of 7Gy x 4 fractions was most commonly employed (77.7%).All the patients received two fractions in single application delivered at the minimum interval of six hours. The mean BED and mean EQD2 of the RT doses employed in this study was 100.13Gy ± 4.54Gy and83.91Gy ± 3.78Gy, respectively. The median follow-up duration was 18 months. The majority of patients were alive on the last follow-up with 3 deaths reported due to disease. Most of the patients developed acute Grade 1 skin (23.3%), gastro-intestinal(GI)(20%) and genitourinary(GU)(8.8%) toxicity. Grade 2 skin, GI and GU toxicity was observed in 8.1, 9.2 and 6.6% respectively. None of the patients experienced Grade 3 and above acute toxicity. Grade 1 late GI toxicity was observed in 3 patients. Material/Methods: Results:

Table 1. Treatment detail

Treatment group

RT Alone

9(20.0)

CT-CCRT

3(6.7)

CCRT alone

33(73.3)

EBRT machine and technique