ESTRO 2021 Abstract Book

S830

ESTRO 2021

Conclusion In a cohort of OPC patients treated uniformly with a 3-dose level prescription, our SoP based on the omission of primary CTV_P2 on a routine basis did not translate into a detrimental effect on LC. Longer follow-up is needed to ascertain its impact on oncologic outcome and late toxicity. PO-0998 Dosimetric predictors of patient-reported taste alteration in head and neck cancer: a cohort study E. Scoccimarro 1 , L.P. Ciccone 1 , S. Caini 2 , M. Aquilano 1 , A. Peruzzi 1 , C. Becherini 1 , L. Livi 3 , I. Desideri 4 , P. Bonomo 5 1 University of Florence, Department of Experimental and Clinical Biomedical Sciences "Mario Serio", Florence, Italy; 2 Institute for Cancer Research, Prevention, and Clinical Network (ISPRO), Cancer Risk Factors and Lifestyle Epidemiology Unit, Florence, Italy; 3 University Of Florence, Department of Experimental and Clinical Biomedical Sciences "Mario Serio". Azienda Ospedaliero Universitaria Careggi, Radiation Oncology Unit - Oncology Department, Florence , Italy; 4 University Of Florence, Department of Experimental and Clinical Biomedical Sciences "Mario Serio", Florence, Italy; 5 Azienda Ospedaliero Universitaria Careggi, Radiation Oncology Unit - Oncology Department, Florence, Italy Purpose or Objective Taste alteration (TA) is a common acute treatment-related side effect in head and neck cancer which contributes to quality of life deterioration and malnutrition. Currently, no organs at risk nor dose constraints are known to allow for the prevention of dysgeusia. The aim of our work was to assess the correlation between dose estimates to the tongue and patient-reported TA. Materials and Methods We performed a single-center, prospective cohort study. Eligible patients had to have locally advanced head and neck squamous cell carcinoma (HNSCC) deemed suitable to curatively-intended treatment. Primary tumors of the oral cavity were not included. The Chemotherapy-induced Taste Alteration Scale (CiTAS), EORTC QLQ-C30 and QLQ-HN43 questionnaires were collected at baseline (T0), 3 weeks after RT conclusion (week 10; T1) and at 3 months (week 19; T2). CiTAS is a validated 18-item scale for evaluating TA induced by chemotherapy. The subdomain “general taste alterations” was evaluated adding the mean values of questions 1, 7-9 and dividing this result by four, as per scoring manual, resulting in a 1-5 score scale. The base of tongue was delineated according to consensus guidelines (Brouwer CL, Radiother Oncol 2015). By dividing the remaining tongue into an anterior and middle third, a prospective consensus delineation of 3 independent physicians was obtained with good internal consistency (data not shown). The mean dose to the 3 tongue subvolumes was correlated with patient-reported outcome measures. Results Between 09/19 and 11/20, 33 patients were included; 31 of them are here analyzed. The primary tumor site was oropharynx (n=22; 71%; HPV status was positive in 13 of them). All patients were treated with Tomotherapy with a 3-dose level SIB technique (69.9, 59.4 and 52.8 Gy in 33 fractions). Most (77.4%) had concurrent cisplatin. The mean scores of general taste alterations (CiTAS subdomain), global health status (items 29 and 30 of QLQ-C30) and dry mouth and sticky saliva (items 42 and 42 of QLQ-HN43) were 1.17, 2.59, 1.83, 69.35, 62.37, 71.39 and 11.29, 49.46, 46.67 at T0, T1 and T2, respectively. The median mean doses to the extended oral cavity, anterior third of the tongue, middle third of the tongue and base of tongue were 32.6 Gy, 22.9 Gy, 32.9 Gy and 50.1 Gy, respectively. At univariate analysis, a significant correlation was found between the mean dose to the middle third of the tongue and the time-trend worsening of general taste alterations (coefficient 0.14; 95% CI: 0.02-0.27, p=0.027) (figure 1). In addition, the mean doses to the anterior and middle thirds of the tongue were significantly correlated with the dry mouth subdomain score (coefficient 8.81, 95% CI: 1.91-15.72, p=0.012 and 5.43, 95% CI: 1.09-9.78, p=0.014, respectively) (figure