ESTRO 2021 Abstract Book

S790

ESTRO 2021

PO-0947 Indications for chest computed tomography in the extension study of HNC J. Pachón Ibáñez 1 , B. Quintana Ángel 1 , A. Wals Zurita 2 , J. Saavedra Bejarano 2 1 Hospital Universitario Virgen del Rocío, Oncología Radioterápica, Seville, Spain; 2 Hospital Universitario Virgen Macarena, Oncología Radioterápica, Seville, Spain Purpose or Objective The incidence of pulmonary metastases (PM) and nonspecific pulmonary nodules (NPN) at the time of diagnosis for squamous cell carcinoma of the head and neck (SCCHN) is varied, likewise, the therapeutic management of these patients is not well defined. For the detection of PM, the computed tomography (CT) multislice is considered the test of choice, having increased the diagnosis of NPN. The standard treatment for metastatic disease is systemic therapy. For a few years, there has been an increase in publications in which a better response is observed, by adding local treatment to systemic treatment. Objetives 1. Anlyze the incidence of PM and NPN. 2. Analyze the time for metastatic conversion of NPN. 3. Analizy the overall survival in function of the treatment received. Materials and Methods Retrospective cohort study of 200 consecutive patients with SCCHN with chest TC, performed at diagnosis. Follow-up was carried out after treatment for at least 3 years. TNM 7th edition was used. Results Only 2 patients (1%) were considered metastatic at diagnosis of SCCHN and 32 patients (16%) presented NPN. In the multivariate analysis, the hypopharynx was the only variable that was statistically significantly associated as a risk factor for presenting NPN. Of the patients with NPN only 10 (31.25%) of these became PM. Thus at the end of follow-up, 12 patients, (6%) had PM. The mean time to detection of metastasis was 15.7 months (+/- 11.5). In the multivariate analysis, patients with hypopharyngeal neoplasia and N2 patients had a statistically significantly higher risk of presenting PM. (p <0.05). Survival was greater in patients who received locoregional treatment despite having PM or NPN. Of the 12 patients with PM, 11 (91.7%) received locoregional treatment with radical intention and only 1 (8.3%) did not. The mean overall survival of patients treated locoregionally with radical intention was 22.1 months (+/- 13.6 months) and 7 months for the patient not treated locoregionally. Conclusion Patients with hypopharyngeal neoplasia and/or stage N2 should have a chest CT at diagnosis. The presence of NPN or PM should not condition the locoregional treatment for presenting greater survival. To our knowledge, this is the first study to jointly analyzes the risk factors associated with the presence of PM and NPN, as well as the therapeutic attitude followed in these patients and survival as a function of the treatment administered. PO-0948 Impact of HPV status on normal tissue toxicities experienced by head & neck cancer patients X. Ray 1 , W. Sumner 1 , L. Sutton 1 , P. Sanghvi 1 , I. Deichaite 1 , V. Moiseenko 1 1 University of California San Diego, Dept of Radiation Medicine and Applied Sciences, San Diego, USA Purpose or Objective In radiotherapy planning, population-based dose criteria for organs-at-risk (OARs) are used as thresholds for normal tissue toxicities. However, it is well established that patients exhibit individual responses to dose, and thus a strong need remains for biomarkers to guide treatment plan personalization. The purpose of this study was to determine if HPV status, a well-known predictor of tumor sensitivity in head & neck cancer patients, may also play a role in their normal tissue outcomes. Materials and Methods A retrospective cohort of 101 patients treated for head & neck cancer at our institution was obtained. For each patient, the mean doses to the pharynx, superior pharyngeal muscles (PGM_sup), middle pharyngeal muscles (PGM_mid), inferior pharyngeal muscles (PGM_inf), and cricopharyngeus was extracted from their radiation treatment plan. Additionally, each patient’s age, sex, and HPV status was catalogued as were the prospectively collected early and late dysphagia scores graded on the CTCAE scale. These toxicities were binarized from 0-2 and 3-5 for statistical analysis. The relationship between HPV status and early and late dysphagia was analyzed with a chi-square test where p-values<0.05 were significant. The relationship between mean dose metrics and each outcome was established using a t-test with p-values<0.05 for significance. Then multi-variate logistic models were built for each binarized outcome as a function of age, sex, HPVstatus, and one dose metric at a time. Covariates with p-values <0.05 were considered significant predictors in each In the chi-square analysis, HPV-negative status was significantly associated with late dysphagia (p=0.028) but not early dysphagia (0.65). In contrast, four of the five dose metrics, pharynx (p-0.032), PGM_Mid (p=0.020), PGM_Inf (p=0.015), and cricopharyngeus (p=0.022) were significantly associated with early dysphagia, but none were associated with late dysphagia. The average dose differences in the mean dose for each structure between patients with low-grade (0-2) response versus high-grade (3-5) response were 7.0Gy (pharynx), 7.1Gy (PGM_Mid), 12.1 (PGM_Inf), and 11.4Gy (cricopharyngeus) respectively. In the logistic models, these trends model. Results