ESTRO 2023 - Abstract Book

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ESTRO 2023

Materials and Methods Retrospective analysis of 40 patients treated according to the “Quad-Shot” regimen between 06/2017 and 05/2022 at the University Medical Center of Mainz. Two daily fractions of 3.5 Gy were delivered with an interval of at least 6 h for two consecutive days, totaling in 14 Gy over four fractions. The treatment was repeated every 4 weeks for a total of 3 cycles. Systemic therapy was administered to 17 (42,5%) patients, 12 (70,5%) of whom received either immunotherapy alone or immunotherapy plus chemotherapy. Palliative response in form of tumor response using RECIST 1.1 criteria and symptom relief were assessed. Toxicity rates according to CTCAE v5.0 and parameters determining patient outcomes were assessed. Kaplan-Meier was used for survival analysis, log-rank test was performed for comparisons between groups, and cox regression was used for multivariate analysis. Results All patients received at least 1 cycle of the “Quad-Shot” regimen, with 19 (47,5%) patients receiving 3 cycles. The most common histology was squamous cell carcinoma (90%). The overall palliative goal was achieved in 36 (90%) patients. 72,5% of patients had objective response to treatment with 1 (2,5%) patient demonstrating complete response (CR), 13 (32,5%) patients demonstrating partial response (PR) and 15 (37,5%) patients demonstrating stable disease (SD). Pain and symptom relief was achieved in 27,3% and 30,4 %, respectively. Median overall survival (OS) and median progression-free survival (PFS) were 4,4 months (range, 2,77-8,03) and 7 months (range, 6,42-NA), respectively. On univariate analysis, a low comorbidity score (p=0.03), a greater number of treatment cycles (p<0.00) and concurrent systemic therapy (p=0.04) were significantly associated with improved OS, while a greater number of treatment cycles (p=0.002) was significantly associated with PFS. Multivariate analysis revealed that completion of the prescribed number of treatment cycles (p<0.001) and a low comorbidity score (p=0.047) remained independent factors for improved OS. Grade 1, Grade 2 and Grade 4 toxicity was observed in 8 (20%), 6 (15%) and 1 (2,5%) patient(s). Grade 4 toxicity consisted of acute radiation dermatitis and was related to concurrent systemic therapy with Cetuximab. Conclusion For patients with advanced head and neck cancers that are not amenable to curative therapy, the palliative ‘Quad-Shot’ regimen with or without concurrent systemic therapy is well-tolerated and provides adequate rates of palliative response. 1 Guy's and St Thomas' NHS Foundation Trust, Clinical Oncology, London, United Kingdom; 2 Guy's and St Thomas' NHS Foundation Trust, Radiology, London, United Kingdom Purpose or Objective Locally advanced oral cavity squamous cell carcinoma (OCSCC) is a distinct disease entity within head and neck cancer. Patients undergo intensive and combined modality treatment with both surgery and post operative radiotherapy (PORT). Overall survival rates are poor however, estimated to be ~50% at 5 years. We require pre-treatment biomarkers to identify which patients will respond well to such treatment. The purpose of this study was to assess the ability of pre-treatment quantitative diffusion weighted MRI (DW-MRI) to predict disease free survival (DFS) and overall survival (OS) in patients with locally advanced OCSCC. Materials and Methods This retrospective study included 50 patients (32 male, mean ± SD age 60.0 ± 12.0 years) with stage III-IV OCSCC who were treated with surgery and PORT, who also had a pre-treatment MRI of the head and neck region. Two independent head and neck radiologists placed regions of interest (ROI) around the maximum cross-sectional area of the primary tumour and the mean apparent diffusion coefficient (ADCmean) was calculated. The ADCmean of the primary tumour was then normalized, using the spinal cord ADCmean as a reference tissue, in order to address difference heterogeneity in MRI parameters. Cox regression tests were conducted to analyse the effect of the pre-treatment ADCmean and the normalised ADCmean on DFS and OS. Statistical analysis was performed using IBM SPSS Statistics 28 software. Results A Bland-Altman analysis showed good inter-observer agreement between the ADCmean (Fig 1) values obtained by the two MRI radiologists. The mean ± SD tumour ADCmean was 1041.9 x 10-6 mm2/s ± 128.2 x 10-6 mm2/s. Neither the primary tumour ADCmean nor the normalised primary tumour ADCmean were able to predict DFS (HR 1.000, p=0.853 and HR 0.466, p=0.510) or OS (HR 1.000, p=0.924 and HR 0.472, p=0.516). PO-1222 Quantitative diffusion weighted MRI does not predict outcome in stage III-IV oral cavity cancer. K. Sambasivan 1 , C. Dudau 2 , T. Guerrero Urbano 1 , S. Connor 2