ESTRO 2024 - Abstract Book

S1192

Clinical - Head & neck

ESTRO 2024

Keywords: radiation-induced toxicity, osteoradionecrosis

References:

Delanian: Complete restoration of refractory mandibular osteoradionecrosis by prolonged treatment with PENTOCLO. Int J Radiat Oncol Biol Phys 2011; 80: 832-9

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Digital Poster

Post-Adjuvant Radiation Failure Pattern Analysis in Bucco-Alveolar complex carcinoma by Focal volume

Akash R Bellige 1 , Sarthak Tandon 1 , Sandeep Purohit 1 , Shamima Akhter 2 , Munish Gairola 1 , Parveen Ahlawat 1

1 Rajiv Gandhi Cancer Institute and Research Centre, Radiation Oncology, New Delhi, India. 2 SSH Hospital Government Medical College, Surgical Oncology, Srinagar, India

Purpose/Objective:

Oral cavity cancers predominantly show a unique pattern of locoregional failure. following a multi-modal intervention, the chances of locoregional failure still continue to remain high. Though surgical intervention is the most commonly advocated primary treatment modality, it is often complicated by the innate anatomy and the complex vasculature of the region. IMRT has caused a paradigm shift in the field of radiotherapy but made the labeling of failures difficult as to whether it is a result of inherent radioresistance or not.1 Delivery laterality of radiotherapy, target delineation and delivery errors, and dose in-homogeneity complicate the assessment of failures.2 A geometric-dosimetric evaluation of recurrences in patients was done in this study to simplify failure analysis and to analyze patterns of failure. Treatment practices concerning radiotherapy target volume definitions and dose prescription are discussed.

Material/Methods:

Eighty-six patients with squamous cell carcinoma of the buccal-alveolar complex treated with surgery followed by radiotherapy and pathological N0-2b during the period of 2018-2021 were enrolled. Patients were grouped on the basis of whether radiotherapy was delivered unilaterally or bilaterally. A comparison of baseline characteristics was done. Focal point and dosimetric methods were used to find the failure pattern, based on the dose received by the region and the anatomic relationship of the recurrent lesion with respect to the surgical bed.3 Pattern of failure with respect to the dose received was classified into types A, B, C, D, and E by creating focal volumes, which denoted recurrences in high-risk volume received more than 95% of prescribed dose, high-risk volume receiving less than 95% of prescribed dose, low-risk volume receiving more than 95% prescribed dose, low-risk volume receiving less than 95% prescribed dose and extraneous disease respectively.4 The recurrent lesions were also assessed based on their anatomical location with respect to the flap margin into the anterior margin, posterior margin/parotid bed, supra notch/ Masticator space, pterygopalatine fossa, infra notch/ pterygoid plates, and posteromedial flap margin