Clinical outcomes of single application multi- fractionated CT-guided interstitial high-dose-rate brachytherapy for locally advanced cervical cancer A multi-institution initial experience

Purpose: The aim of the study was to evaluate the safety and clinical outcomes of single application multi -fraction-ated computed tomography (CT)-guided interstitial high-dose-rate brachytherapy given in four fractions in locally advanced cervical cancer.Material and methods: Patients with locally advanced cervical cancer stage IIB-IVA treated definitively with external radiation +/- weekly cisplatin, followed by single application multi-fractionated CT-guided interstitial high-dose-rate brachytherapy in four fractions were included. Dosimetry data, clinical response, and toxicity records were reviewed. Results: Between January 2018 and December 2022, twenty-two patients were included. Clinical stage distribution was as follows: IIB - 13.6%, IIIB - 27.3%, IIIC - 22.7%, and IVA - 36.4%. Mean high-risk clinical target volume (HR-CTV) was 66.19 +/- 32.69 cm3, and HR-CTV D90 dose was 86.8 +/- 1.7 Gy. 2 cc doses to bladder, rectum, and sigmoid were 84.6 +/- 2.8 Gy, 71.5 +/- 2.4 Gy, and 65.6 +/- 4.0 Gy, respectively. Mean overall treatment time was 66 +/- 21 days. With a median follow-up of 11.5 months (range, 5-44 months), median survival and local control were not achieved. One-year local control rate, one-year progression-free survival, and one-year overall survival were 82%, 66%, and 78%, respectively. Univariate analysis showed overall treatment time to be the only variable associated with all oncologic outcomes. For acute toxicity, grade 3 toxicity in four patients and grade 4 toxicity of infection in one patient were ob served. For late toxicity, grade 3 gastrointestinal toxicity was noted in two patients.Conclusions: Initial results suggest that single application multi-fractionated CT-guided interstitial brachytherapy given in four fractions in locally advanced cervical cancer seems to be feasible and safe, but additional evidence is needed to generate more validated conclusions.