ESTRO 2023 - Abstract Book

S952

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ESTRO 2023

The median time for ORN development, which was predominantly in the mandible, was 21 (range 1 – 100) months. ORN was graded as Notani grade 1, 2 and 3 in 48.9, 8.5, 42.6% respectively. On comparison of patients with ORN who underwent pre-RT surgery versus no surgery, higher Notani grade (3 vs 1) (p<0.02), shorter time to development since RT (<12-months)) p=0.044) and less likelihood of resolution (p=0.019) was statistically significantly associated with patients who underwent pre-RT surgery. Conclusion This study is the first study to investigate the incidence of ORN in HNC patients in Ireland. These findings may further aid in the clinical management and prevention of ORN in HNC patients.

PO-1190 Case-control study of clinical and dosimetric factors associated with OsteoRadioNecrosis of the Jaw.

M. Renouf 1 , S. Auger 2 , C. Dupas 2 , L. Campion 3 , G. Delpon 4 , P. Bléry 2 , M. Doré 1

1 Institut de Cancérologie de l'Ouest René Gauducheau, Radiotherapy, Saint-Herblain, France; 2 Centre Hospitalier Universitaire, Odontology, Nantes, France; 3 Institut de Cancérologie de l'Ouest René Gauducheau , Biostatistics, Nantes, France; 4 Institut de Cancérologie de l'Ouest René Gauducheau, Physics, Saint-Herblain, France Purpose or Objective OsteoRadioNecrosis of the Jaw (ORNJ) is a rare but severe complication of head and neck irradiation. Tooth extractions before radiation, surgery, tumor location, high volume of mandible receiving 60 Gy and high mean dose to mandible are well-known risk factors of ORNJ. However, there is still debate regarding dosimetric factors, especially in the Intensity modulated Radiation Therapy (IMRT) era, because of heterogenous dose distribution to mandible. We conducted a case control study to evaluate clinical and dosimetric factors associated with ORNJ in a cohort of patients treated for carcinoma of the oral cavity (OC) or oropharynx (OR). Materials and Methods From 2008 to 2019, patients treated with IMRT for OC or OR carcinoma were included. To each ORNJ case, we assigned 2 controls matched to cases on tumor location (OR/OC), surgery prior to Radiotherapy, smoking status, gender, age. Patient and treatment related data were retrospectively collected. We used the Dosimetric Evaluation of Risk of Osteoradionecrosis (DERO) tool to extract dosimetric data in each dental sector. We searched for clinical and dosimetric factors associated with ORNJ using univariate and multivariate analysis. Results Out of 897 patients treated for OR or OC carcinoma with IMRT in our center, 59 patients with ORNJ were included and matched to 118 controls. Median follow-up was 5.3 years in the ORNJ group and 4.5 years in the control group (p=0.34). Median time to ORNJ diagnosis was 1 year (0.18; 8). In univariate analysis, post-radiation dental extractions, diabetes, mucositis > grade 2, and lymph node involvement were associated with higher risk of ORNJ. In multivariate analysis, only post-radiation dental extractions (p=0.004) and diabetes (p=0.04) remained significantly associated with ORNJ. Dosimetric factors associated with ORNJ in multivariate analysis were V58 Gy (Volume of mandible exposed to 58 Gy) (p = 0.04), V60 Gy (p=0.04), Mean Dose to mandible (p=0.025). Mean dose in dental sectors was significantly associated with ORNJ (p<0.0001), especially when mean dose exceeds 54 Gy. Conclusion Our findings support well-known clinical and dosimetric factors associated with higher risk of ORNJ, such as post-radiation dental extractions, diabetes, V58Gy, V60Gy and Mean dose to mandible. To our knowledge this is one of the first studies assessing anatomic correlation between dose to dental sectors and ORNJ location. A. Biswas 1 , V. Ghosh 1 , S. Roy 1 , S. Bhasker 1 , A. Binjola 1 , M. Tripathi 2 , A. Kakkar 3 , R. Pramanik 4 , A. Sharma 4 , S. Ghose 4 , A. Thakar 5 , K. Rangarajan 6 , C. S.H. 6 , C. Bal 2 , R. Malhotra 7 1 All India Institute of Medical Sciences, New Delhi, Radiation Oncology, New Delhi, India; 2 All India Institute of Medical Sciences, New Delhi, Nuclear Medicine, New Delhi, India; 3 All India Institute of Medical Sciences, New Delhi, Pathology, New Delhi, India; 4 All India Institute of Medical Sciences, New Delhi, Medical Oncology, New Delhi, India; 5 All India Institute of Medical Sciences, New Delhi, Otorhinolaryngology, New Delhi, India; 6 All India Institute of Medical Sciences, New Delhi, Radiodiagnosis, New Delhi, India; 7 All India Institute of Medical Sciences, New Delhi, Delhi Cancer Registry, New Delhi, India Purpose or Objective We assessed the serial changes in health related quality of life(HR-QoL) parameters in patients with locally advanced nasopharyngeal carcinoma(LA-NPC) on a phase 2 clinical trial of gemcitabine and cisplatin(GC) based neoadjuvant chemotherapy(NACT) followed by dysphagia optimised intensity modulated radiotherapy(Do-IMRT) with concurrent weekly cisplatin. Materials and Methods Patients with stage II-IVA NPC received 3 cycles of 3-weekly NACT with cisplatin and gemcitabine followed by Do IMRT(65Gy,60Gy,54Gy/30fractions/6weeks to high-risk, intermediate-risk and low-risk PTVs respectively by simultaneous integrated boost) with concurrent weekly cisplatin. Serial changes in HR-QoL were assessed by European Organisation for PO-1191 Health related QoL in patients with NPC treated with NACT followed by dysphagia-optimised CRT