HIGH DOSE RATE BRACHYTHERAPY IN THE TREATMENT OF CERVICAL CANCER: RETROSPECTIVE STUDY ABOUT 380 PATIENTS, EXPERIENCE OF THE NATIONAL INSTITUTE OF ONCOLOGY, RABAT

Introduction: Brachytherapy is an essential component in the treatment of women with cervical cancer, significantly improving overall survival and local control rates.The objective of the study is to present the Moroccan experience of the Rabat National Institute of Oncology in high-dose-rate (HDR) brachytherapy for cervical cancer.

Material and Methods: Retrospective study from January 2019 to December 2023carried out in the radiotherapy department at the National Oncology Institute Rabat describing the clinical, paraclinical, technical, dosimetric and evolutionary modalities of three-dimensional high-dose-rate brachytherapy in 380 patients with cervical cancer. These data were then entered and processed on Microsoft Excel 2019.

Results:The patients had a mean age of 54 years, with squamous cell carcinoma as the predominant histological type (88%), followed by adenocarcinoma (12%).In our study, pelvic MRI was performed in 98% of patients, with tumor stages according to the FIGO 2018 classification being IB (6.6%), IIA (5,8%), IIB(34,2%), IIIC1(21.6%), IIIC2 (14.7%), and IVA bladder and rectal (17.4%) respectively.All patients were treated with external beam radiotherapy with a dose of 46 Gy concomitantly with weekly cisplatin at a dose of 40mg/m2. The average total course of external beam radiotherapy combined with brachytherapy was 66 days [44-75]. 90% of applications were intracavitary and 10% were vaginal brachytherapy. The applications were controlled by per-brachytherapy ultrasound.The protocols used for intracavitary brachytherapy were 4x7Gy weekly in 29.5% of cases, 4x7Gy in two series in 50% of cases, 3x8Gy weekly in 12% of cases, and for barrage brachytherapy were 2x5Gy weekly in 4% of cases, 2x6Gy weekly in 2% of cases and 3x6Gy weekly in 2.5% of cases.Brachytherapy dosimetry was performed on a dosimetric scanner for all patients, except for barrage brachytherapy.The mean total EQD2 (α/β 10) external radiotherapy and brachytherapy for high-risk CTV was 94.93Gy. For organs at risk, the mean total EQD2 (α/β 3) external radiotherapy and brachytherapy was 65.5Gy, 61.4Gy, 53.5Gy and 50.2Gy respectively for the bladder, rectum, sigmoid and small bowel. Acute toxicity ofbrachytherapy was represented by minimal bleeding in 9% of patients, grade I cystitis in 3.5% of patients, and grade I radio-mucositis in 2.5%, while 85% of patients had no side effects during the treatment.After a 32-month follow-up, a complete remission was observed for 89,73% of patients, a stable tumor for 2,36% and a local recurrence for 7,89% of women with initial stages IIB, IIIC1 and IVA.

Conclusion:HDR brachytherapy has an important place in the treatment of cervical cancer. It improves local control by reducing locoregional recurrence and toxicity in organs at risk, and improves quality of life after irradiation.