The application of high-dose-rate brachytherapy in the treatment of postoperative floor of the mouth tumours and dosimetric comparison with modern external beam radiotherapy modalities in localization of floor of the mouth and tongue tumours
Ferenczi Örs
Pathological and Oncological Divison
Dr. Matolcsy András
Országos Onkológiai Intézet
2025-02-13 10:00:00
Clinical Oncology and Radiation Therapy
Dr. Polgár Csaba
Dr. Takácsi-Nagy Zoltán
Dr. Bogdán Sándor
Dr. Bellyei Szabolcs
Dr. Németh Zsolt
Dr. Smanykó Viktor
Dr. Varga Linda
Objective: This dissertation explores the effectiveness of high-dose-rate (HDR) brachytherapy as a postoperative radiotherapy technique for treating squamous cell carcinomas of the floor of the mouth. It presents a komparatívéi dosimetric analysis between HDR brachytherapy and modern external beam radiotherapy (EBRT) techniques, including volumetric-modulated arc therapy (VMAT) and Cyberknife (CK).
Background: Oral cavity carcinomas are among the most common cancers worldwide, with significant mortality. Current radiotherapy methods, such as IMRT and VMAT, allow precise targeting while sparing critical organs. Brachytherapy, with its direct application of radiation near or within the tumour, offers a highly localized dose distribution, reducing exposure to surrounding tissues. Historically, low-dose-rate (LDR) brachytherapy was standard, but HDR techniques have gained popularity due to improved safety and precision.
Methodology:
1. Clinical Study (Group A): A retrospective analysis of 44 patients treated with postoperative HDR brachytherapy between 1998 and 2017. Tumour stages ranged from pT1-3pN0-1M0. Outcomes such as local control (LC), regional control (RC), disease-specific survival (DSS), and overall survival (OS) were assessed.
2. Dosimetric Comparison (Group B): Twenty cases were evaluated to compare HDR brachytherapy with VMAT and CK using identical dose prescriptions (45 Gy in 15 fractions). Metrics included conformity index (COIN), homogeneity index (HI), and dose exposure to organs at risk (OARs).
Results:
• Group A: The 5- and 10-year LC rates were 89%, with RC rates of 73% and 67%. DSS was 66% (5 years) and 54% (10 years). The most significant prognostic factor was lymphovascular invasion, affecting RC, DSS, and OS. Grade 4 complications, including soft tissue necrosis, occurred at EQD2(3) doses ≥59.7 Gy. No cases of osteoradionecrosis were reported.
• Group B: HDR brachytherapy provided superior sparing of the mandible compared to VMAT and CK. CK offered the lowest dose to salivary glands, while VMAT had the highest OAR exposure. CK demonstrated better conformity, but VMAT had superior homogeneity.
Conclusions:
• HDR brachytherapy is effective and comparable to other modalities for managing early-stage oral cavity tumours. It provides excellent dose conformity with reduced toxicity.
• In cases with positive or close surgical margins, HDR brachytherapy enhances local control, supporting its postoperative use.
• Further research is necessary to optimize neck management strategies and explore stereotactic radiotherapy’s role in postoperative care.
Clinical Implications: This research reinforces HDR brachytherapy’s role in modern radiotherapy for oral cancer, balancing efficacy and reduced complication risks.
