ESTRO 2020 Abstract Book

S456 ESTRO 2020

Conclusion TB is associated with high risk WPOI and infiltrative pattern of invasion. High risk WPOI has association with PNI and infiltrative pattern of invasion and DOI > 10 mm is associated with higher nodal stage. Prospective reporting and documentation of these factors would help in future clinical correlation with failure patterns and help in elucidating the role of these entities as prognostic factor. PO-0845 Role of postoperative RT (PORT) after compartmental surgery for locally advanced oral cavity tumors D. Alterio 1 , M. Augugliaro 1 , M. Tagliabue 2 , G. Marvaso 1 , R. Bruschini 2 , A. Ferrari 1 , O. Oneta 1 , M.A. Zerella 1 , I. Turturici 1 , M. Ansarin 2 , R. Orecchia 3 , B.A. Jereczek-Fossa 1 1 IEO- European Institute of Oncology IRCCS- Milan, Division of Radiotherapy, Milan, Italy ; 2 IEO- European Institute of Oncology IRCCS- Milan, Division of Otolaryngology and Head and Neck Surgery, Milan, Italy ; 3 IEO- European Institute of Oncology IRCCS- Milan, Scientific Directorate, Milan, Italy Purpose or Objective Literature data on the role of postoperative radiotherapy (PORT) in locally advanced oral cavity tumors derived mainly from patients (pts) treated with a wide excision (non-compartmental) surgical approach. Therefore, the role of PORT after compartmental surgery (CS) has not been yet fully investigated. Moreover, preliminary data on pts treated with CS showed that the tract between primary tumor and neck lymph nodes (T-N tract) could represent a prognostic factor for Overall Survival (OS) in such cohort of patients. Therefore, we performed a retrospective analysis on pts treated with CS and PORT (+/- concurrent chemotherapy) treated at our Institute between 2000 and 2016. The impact of T-N tract was also evaluated. Material and Methods Inclusion criteria were: 1) locally advanced (stage III and IV, TNM 7 th ed) oral cavity tumors 2) no previous tumor and/or oncologic treatments in head and neck region 3) CS performed for oral cavity tumors 4) minimum follow of 6 months from surgery. Clinical outcome (in terms of overall survival – OS- and local relapse free survival-LRFS) and impact of T-N tract were investigated. Results One hundred and fifty-seven pts (107 male, median age 54 years, range 17-81 years) were analyzed. Sixty-one (45%) were treated with adjuvant concurrent chemoradiation. After CS, 20 pts (12.4 %) were not treated with subsequent PORT for non-oncologic reasons (pts refusal -76%, delay in surgical healing- 5% , peri-surgical complication - 19%). After a median follow up of 77 months (range 7-198 months), 80 (51%) pts were alive without disease, 18 (11.5%) were alive with local and/or distant metastases or second tumor, 43 (27.5%) dead for tumor progression, 8 (5%) dead for other causes and 8 dead for unknown causes. Tumor, lymph nodes and both tumor and lymph node recurrences were found in 15 (9%), 18 (11%), and 5 (3%) pts, respectively. In order to evaluate the impact of adjuvant radiotherapy we compared the cohort of patients treated with CS followed by PORT (137 pts - 80%) with that treated only with CS (20- 20%). The two cohorts resulted to be comparable except for N stage with a slight imbalance in favor of patients not treated with PORT. Pts treated with PORT resulted to have a better results in OS and LRFS both at univariate (p=0.043, p=0.051, respectively) and multivariate analysis (p=0.01, p=0.012, respectively). In pts not submitted to PORT, the T-N tract confirmed its prognostic role (Fig.1 and Fig.2). Moreover, PORT showed to increase both OS and LRFS in pts with positive T-N tract but not in those with negative T-N tract.

Conclusion Preliminary results showed that PORT seems to maintain its role in increasing both OS and LRSF after CS. Interestingly, this advantage was more evident among patients with positive T-N tract. PO-0846 Preliminary outcome results of a PET-CT based direct planning protocol in head and neck radiotherapy S. Di Biase 1 , F. Perrotti 1 , G. Pavanato 1 , G. Montesi 1 , G. Virdis 1 , A. Ferretti 2 , E. Bellan 2 , L. Rampin 3 , M. Maffione 3 , G. Mandoliti 1 1 Santa Maria della Misericordia Hospital, Radiotherapy department, Rovigo, Italy ; 2 Santa Maria della Misericordia Hospital, Medical Physics department, Rovigo, Italy ; 3 Santa Maria della Misericordia Hospital, Nuclear Medicine department, Rovigo, Italy Purpose or Objective We report treatment planning implications and early clinical outcome of a simulation PET-CT (sPET-CT) and direct planning protocol in head and neck (H&N) cancer radiotherapy (RT). Material and Methods Twenty-two consecutive H&N cancer patients underwent to an optimized procedure of sPET-CT in RT set-up (flat top, mould), using a specific PET acquisition protocol (2 beds, matrix 400x400, 6 minutes/bed). Gross tumor volume (GTV) was delineated using an automated threshold method at 50% of the intralesional SUV max. Clinical target volume (CTV) was obtained adding a 9-mm isotropic margin, respecting anatomical boundaries. A 3- mm margin was added to generate the planning target volume (PTV). Volumetric modulated arc therapy (VMAT) plans were designed by including also elective nodal stations as indicated. To assess early clinical outcome the first evaluation, with PET-CT and/or CT plus clinical examination, was performed 2 months after RT, then every 3 months. Results All 22 enrolled patients showed GTV evidence on PET-CT at baseline. Subsites involved were: oral cavity (5), oropharynx (7), larynx (7), hypopharynx (1), nasopharynx