ABSTRACT
Purpose: The aim of the study was to evaluate the safety and clinical outcomes of single application multi-fractionated 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 observed. 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.
ABSTRACT
PURPOSE: In nasopharyngeal cancer, brachytherapy is given as boost in primary treatment or as salvage for recurrent or persistent disease. The Rotterdam nasopharyngeal applicator (RNA) allows for suboptimal reduction of soft palate radiation dose, based on image-guided brachytherapy plans. Building on the RNA, we propose a novel design, the Benavides nasopharyngeal applicator (BNA). METHODS AND MATERIALS: The virtual BNA was reconstructed on two cases (one T1, one T2) previously treated with intracavitary brachytherapy using the RNA. Dose was prescribed to the high-risk clinical target volumes (CTVs) and optimization was such that high-risk CTV D90 ≥ 100% of prescribed dose (PD), intermediate-risk-CTV D90 ≥ 75% PD, and soft palate D2cc ≤ 120% PD. The optimized RNA and BNA image-guided brachytherapy plans were compared in terms of CTV coverage and organs-at-risk sparing. RESULTS: Optimization objectives were more easily met with the BNA. For the T1 case, all three planning objectives were easily achieved in both the RNA and BNA, but with 18-19% lower soft palate doses with the BNA. For the T2 case, the CTV planning objectives were achieved in both the RNA and BNA, but the soft palate constraint was only achieved with the BNA, with 38-41% lower soft palate doses. CONCLUSIONS: Compared to the RNA, the BNA permits easier optimization and improves therapeutic ratio by a significant reduction of soft palate doses, based on simulation using a proposed system for CTV/organs-at-risk delineation, prescription, and optimization for image-guided adaptive brachytherapy. Clinical piloting using a prototype is necessary to evaluate its feasibility and utility.