ESTRO 2022 - Abstract Book

S943

Abstract book

ESTRO 2022

J. Lee 1

1 Yonsei Cancer Center, Radiation Oncology, Seoul, Korea Republic of

Purpose or Objective Human papillomavirus (HPV)-associated tonsillar cancer has a better prognosis than HPV-negative cancer, so deintensification strategies to reduce or exclude radiotherapy (RT) have been suggested through several studies. However, there is no strong evidence or guidelines for deintensification of RT. In this study, we investigated the treatment outcome in patients with HPV-associated tonsillar cancer and provide deintensification strategy for RT. Materials and Methods Retrospective cohort study of patients with clinical stage T1-4N0-3 HPV-associated tonsillar cancer treated between 2008 and 2020 with primary surgery or RT. Overall survival (OS), progression-free survival (PFS) and cumulative incidence of locoregional failure (LRF) between primary surgery and primary RT were analyzed, and propensity score matching was performed to adjust for clinical factors. The following subgroup analysis was conducted for patients who received primary surgery; The difference in LRF according to adjuvant RT, prognosis differences according to pathological response after neoadjuvant chemotherapy, and risk factors related to contralateral regional failure in initial contralateral neck lymph node (LN)-negative patients. Results Of the total patients, 84 patients (22.5%) received primary surgery alone, 224 patients (59.9%) received primary surgery plus adjuvant RT, and 66 patients (17.6%) received primary RT. After adjusting for clinical factors, there was no statistical difference in OS, PFS, and LRF between the primary surgery group and the primary RT group. In subgroup analysis, advanced pathologic N stage, contralateral LN metastasis at diagnosis, abutting or positive surgical resection margin, and no adjuvant RT were independent risk factors of LRF in patients undergoing primary surgery. There was no locoregional failure or death among 22 patients who had received neoadjuvant chemotherapy before surgery and achieved pathological complete remission. Among them, 15 patients (68.2%) did not receive adjuvant RT. Among 282 initial contralateral neck LN-negative patients who underwent primary surgery, 8 patients had contralateral regional failure. None of these patients underwent contralateral neck dissection, and all resection margins were less than 1 mm or positive. In multivariate analysis, lymphovascular invasion and elective contralateral neck irradiation not higher than 30.6 Gy were independent risk factors of contralateral regional failure. Conclusion In patients undergoing primary surgery, adjuvant RT can reduce LRF, and can be further considered, especially for advanced N stage or abutting or positive resection margin. Contralateral regional failure occurred in only 2.8% of initial contralateral neck LN-negative patients who underwent primary surgery. However, for patients who have adverse features such as lymphovascular invasion and close resection margin and have not undergone contralateral neck dissection, elective contralateral neck irradiation with a dose higher than 30.6 Gy can be considered. Purpose or Objective Incidence of head and neck (H&N) cancer is related to increasing age, with more than a fifth of UK cases in those aged over 75, and closely correlated to deprivation. 1 The West of Scotland (WOS) has some of the worst areas of socio-economic deprivation and life expectancy for those areas is lower than the UK average. 2 Approximately 5% 2 of all H&N cancers arise from the hypopharynx. Patients with hypopharyngeal squamous cell cancers (HPSCC) tend to have a poor prognosis compared with other subsites. The UK survival for HPSCC at 1 year is 60% and 27% at 5 years. Survival for HPSCC is higher in women and younger patients. 2 Only 1-2% of HPSCC cases are T1N0 and 80% are stage III/IV at presentation. 3 There are very few HPSCC-specific studies and this subsite is not well represented in general H&N trials. Thus, deciding the best treatment plan is difficult and relies on the expertise of a multi-disciplinary team (MDT). 4 The challenges of older age, Materials and Methods This was a retrospective series of histologically or radiologically diagnosed HPSCC made from August 2016 to August 2018, identified from the WOS Cancer Network MDT database. Subsites included pyriform fossa, post cricoid and posterior pharyngeal wall. Results 118 patients were evaluable. 35.6% were aged >70 and 33.1% were PS 2+. 26.3% patients had a prior cancer diagnosis, with 16% having a previous H&N cancer. PET-CT was performed in 11.5% of the T4 patients. 5 (4.24%) were upstaged post- operatively. For stage 1-2 patients, primary surgery (PS) had a 100% overall survival (OS) at 2 years compared with radiotherapy (RT) alone (64.8%, CI 25.3-87.2). co-morbidities and advanced stage compound the difficulty in treating these patients. The aim of this series was to review outcomes of HPSCC patients in our cancer network. PO-1110 Survival outcomes in Hypopharyngeal Squamous Cell Cancers in the West of Scotland Cancer Network W. Poon 1 , C. Paterson 1 , P. McLoone 1 , D. Grose 1 , A. James 1 , C. Lamb 1 , S. Schipani 1 , C. Wilson 1 1 Beatson West of Scotland Cancer Centre, Clinical Oncology, Glasgow, United Kingdom