ESTRO 2020 Abstract book

S482 ESTRO 2020

and 74.7% male distribution. Patient diagnoses included oropharynx (29.7%), oral cavity (15.9%), laryngeal (17.6%) or other (36.8%). Among 3189 (86.2%) who underwent dental assessment pre-radiation,, 7.2% had public insurance, 48.1% private insurance, and 44.7% no dental insurance. Overall, 512 patients (14%) were not assessed in the dental department. Patients with public or no dental insurance had a significantly higher proportion of their dentition removed pre-radiation (16.3%, standard deviation/SD=29.7 and 9.7%,SD =22.2 respectively) compared to patients with private dental insurance (5.0%,SD=15.8) (p<0.001). Multivariate analysis of 2908 patients (793 edentulous patients excluded) showed that dental insurance status was independently associated with pre-radiation tooth removal adjusted by dental provider, missing surfaces, decayed or filled surfaces, gender, disease site, nodal status and smoking status (p<0.001), with adjusted Odds Ratio (95% Confidence Interval) of 2.87 (2.56-3.21) for public dental insurance and 2.00 (1.85- 2.16) for no dental insurance (both p<0.001). Imputation on dental insurance status of the insurance status unknown patients (n=512) using the insurance status known patients (n=3189) and confirmed that dental insurance status was associated with compliance with pre-radiation dental assessments. Conclusion Dental insurance status significantly associated with prophylactic dental treatment provided pre-radiation for head-and-neck cancer. In addition, dental insurance status may impact patient access to medically necessary prophylactic dental care even within a universal healthcare setting. PO-0806 Prognostic value of eosinophil levels in oropharyngeal cancer: a retrospective multicentric study F. Olivero 1 , P. Franco 1 , F. Ferreri 1 , A. Casadei Gardini 2 , K. Andrikou 2 , F. Arcadipane 3 , A. Gastino 1 , V. De Luca 1 , S. Cascinu 4 , U. Ricardi 1 1 University of Torino, Department of oncology- Radiation oncology, Torino, Italy ; 2 Policlinico di Modena AOU, Department of Medical and Surgical Sciences for Children and Adults- Division of Medical Oncology, Modena, Italy ; 3 AOU Citta' della Salute e della Scienza, Department of Oncology- Radiation Oncology, Torino, Italy ; 4 University Vita-Salute San Raffaele, Department of medical oncology, Milano, Italy Purpose or Objective Oropharyngeal squamous cell carcinoma (OPSCC) represents a frequent malignancy in the head and neck region. HPV-related OPSCCs are increasing in incidence and HPV positivity is an established prognostic factor predicting for better response rate to chemoradiation and better prognosis. However over 20% of this subset patients dies of OPSCC. The aim of the present study was to evaluate the eventual prognostic value of baseline eosinophil count, in terms of OS comparing outcomes between p16+ve and p16-ve patients. Material and Methods In this retrospective multicentric study, we collected data of all OPSCCs patients treated between 2007 and 2018. All patients recruited had bioptical diagnosis with p16 evaluation (and/or HPV determination with PCR) and eosinophil values at baseline defined as the value within 40 day before starting any treatment. Results We obtained data of 168 patients who met the inclusion criteria: 122 patients p16+ve (of whom 71 with eosinophil value >100 10³/µl and 36 <100 10³/µl) and 46 patients p16- ve (of whom 36 with eosinophil value >100 10³/µl and 10 <100 10³/µl). Among p16+ve patients we observed better OS in the group with eosinophil <100 10³/µl: mean OS was 96.1 months in <100 10³/µl eosinophil group vs 70,9 months in the group with >100 10³/µl; Chi-squared test:

The 2- and 5-years DFS rates were 78% and 73%, and the 2- and 5-years OS rates were 77% and 65%, respectively. On univariate analysis, DFS was associated with HPR ( p =0.015) and lymphovascular invasion (LVI) ( p <0.001). OS was associated with HPR ( p =0.007), LVI ( p <0.001) and positive or close margins ( p =0.044), but in stage III-IVA was not significant ( p =0.127). On multivariate Cox regression, the presence of LVI was a significant predictor of worse DFS (HR 18.23, p =0.002) and OS (HR 5.37, p =0.006). The 3y- DFS stage III-IVA pts who didn’t perform ND was 100% vs. 64% who perform, p =0.060. The 3y-DFS of high HPR pts who didn’t perform ND was 69% vs. 65% who perform, p =0.629. The 3y-OS of patients with stage III-IVA who didn’t perform ND was 69% vs. 64% who perform, p =0.493. The 3y-OS of high HPR pts who didn’t perform ND was 50% vs 64% who perform, p =0.822. The 3y-DFS of pts who perform tumor bed and neck irradiation without ND was 88% vs. 71% with ND ( p =0.211), while 3y-OS was respectively 66% vs. 73% Histopathological and stage features are known prognostic factors for mSGT. DFS and OS improvements were not observed with ND in high-risk histology and III-IV stage disease due to study limitations. Benefit of neck irradiation was not evident regardless of ND status. Some of the results shown, although with no statistically significant differences, could reveal the possible usefulness of AR in pts unable to do ND. Further research of treatment strategies (eg.: selection for ND with/without irradiation) should be investigated in multicentric trials if possible due to the scarcity and heterogeneity of mSGT. PO-0805 Dental insurance status influences prophylactic dental care prior to head and neck radiation E. Watson 1 , W. Xu 2 , M. Giuliani 3 , J. Huang 2 , S. Huang 3 , B. O'Sullivan 3 , J. Ringash 3 , A. Hosni 3 , J. Kim 3 , J. Waldron 3 , A. Bayley 3 , J. Cho 3 , S. Bratman 3 , D. Goldstein 4 , W. Maxymiw 1 , M. Glogauer 1 , A. Hope 3 1 Princess Margaret Cancer Center, Dental Oncology, Toronto, Canada ; 2 University Health Network, Biostatistics, Toronto, Canada ; 3 Princess Margaret Cancer Center and University of Toronto, Radiation Medicine Program and Department of Radiation Oncology, Toronto, Canada ; 4 University Health Network and University of Toronto, Head and Neck Surgery, Toronto, Canada Purpose or Objective Radiation-therapy is a primary treatment for head-and- neck cancer and can result in significant long-term oral side effects including osteoradionecrosis. At our tertiary- care centre, all patients with head-and-neck cancer receiving oral radiation should be referred for dental evaluation pre-radiation per institutional policy. Here, the impact of dental insurance status was assessed on provision of prophylactic dental care pre-radiation for Retrospective cross-sectional study of pre-radiation dental assessments and charts was performed on consecutive head-and-neck cancer patients who fulfilled eligibility criteria: 18 years of age or older, planned for curative radiation of 45Gy or higher, no prior RT. Endpoints included compliance with pre-radiation dental assessment and rates of extraction for those patients who attended the appointment. Univariable and multivariable analyses were performed to assess the impact of dental insurance status on rates of prophylactic dental extractions pre- radiation for head-and-neck cancer when accounting for patient, tumor, and systems factors. Results During the study period, 3701 head-and-neck cancer patients were treated with radiation, mean age 62.9(12.9) ( p =0.981). Conclusion head-and-neck cancer. Material and Methods