ESTRO 2025 - Abstract Book

S1096

Clinical – Head & neck

ESTRO 2025

Purpose/Objective:

To evaluate the frequency and trends of re-planning in patients undergoing adjuvant radiation therapy (RT) for oral cavity cancer and its association with various flap reconstruction techniques, aiming to optimize treatment.

Material/Methods: A prospective analysis was conducted from January 2023 till November 2024. Patients with histopathologically confirmed Squamous Cell Carcinoma of the Oral Cavity (SCCOc) undergoing flap reconstruction and requiring re planning during adjuvant RT with curative intent were included. Re-planning was necessitated by anatomical changes, as determined by weekly imaging and clinical assessments. Results: Among 114 patients undergoing re-planning, 38 eligible patients were identified (33.4%). The mean age was 46 years (SD12), and most were male (37, 97.4%). Most of them had locally advanced SCCOc with Grade-II disease (21, 55.3%). The distribution of flap types included anterolateral thigh flap (ALTF) (19, 49.9%), pectoralis major flap (9, 23.7%), radial forearm flap and free fibular flap in 4 patients each (10.4%) and nasolabial flap and supraclavicular shoulder flap in 1 patient each (2.6%). The mean re-planning week was 4.5 (SD 1.4). The trends of re-planning varied by flap type. Patients with ALTF had a median re-planning at fraction number 22; radial forearm flap and pectoralis major flap showed the earliest trends, with median of the 17th and 18th fraction, respectively. Free fibular flap and supraclavicular shoulder flap were re-planned by the 26th fraction, while the nasolabial flap had a median of the 20th fraction. However, no statistically significant differences were observed in the number of fractions at re-planning across flap types ( p = 0.14 ). Conclusion: Our study suggests that the differences in the trends in re-planning and flap types are not substantial enough to indicate a significant relationship. These findings can be due to low frequency of re-planning and limited sample size. Further research is required to explore multidisciplinary factors that could enhance treatment efficiency. Digital Poster Radiological Depth of invasion as a surrogate for need of nodal dissection in oral cavity cancers: A retrospective anlaysis. Pragyat Thakur 1 , Ankur Dwivedi 2 , Deepander Singh Rathore 2 , Tapas Dora 1 , Varinda Kajal 1 , Alok Goel 3 , Sankalp Sancheti 4 , Anshul Sharma 5 , Ashish Gulia 5 1 Radiation Oncology, Homi Bhabha Cancer Hospital and Research Centre, Sangrur, India. 2 Radiology, Homi Bhabha Cancer Hospital and Research Centre, Sangrur, India. 3 Medical Oncology, Homi Bhabha Cancer Hospital and Research Centre, Sangrur, India. 4 Pathology, Homi Bhabha Cancer Hospital and Research Centre, Sangrur, India. 5 Surgical Oncology, Homi Bhabha Cancer Hospital and Research Centre, Sangrur, India Purpose/Objective: Oral cancer is the sixth most common cancer worldwide, accounting globally for 377,713 new cases in 2022, representing an increase in new cases from 2018. Oral cancer is a major problem in the Indian subcontinent with age-adjusted rates of oral cancer in India as high as 20 per 100,000 population and accounts for over 30% of all cancers in the country. Depth of Invasion (DOI) and cervical lymph node involvement are important prognostic features of oral cavity squamous cell cancers (OCSCC). Consequently, DOI may be predictive of presence of nodal disease. Additionally radiological DOI (rDOI) may be evaluated to be a surrogate for pathological DOI (pDOI). Keywords: re-planning, flap reconstruction 3703