ESTRO 2021 Abstract Book

S801

ESTRO 2021

Median follow up was 42 months [25-62]. The 3-year OS was 85% for the low volume patients (<99.2 ml) versus 30.2% for the high volume patients (>99.2 ml) (p=0.016). The 3-year DFS was 79.7% and 16.8% for the low and high volume patients respectively (p=0.002). The ROC curves showed that the prognostic value of the 8 th edition SS was better than that of the 7 th edition in terms of OS (AUC=0.753 versus 0.728 respectively; p=0.004) and DFS (AUC=0.752 versus 0.704; p= 0.002). The prognostic value of the GTV was better than those of both the 7 th and the 8 th edition SS in terms of OS (AUC=0.878; p<0.001) and DFS (AUC=0.894; p<0.001). Conclusion The overall stages of the 8th edition SS provide better survival prediction than the 7th edition. Our results show that regardless of tumor staging, high volume NPC has an important prognosis impact and should be considered to adapt treatment strategies. PO-0964 Survival outcomes of hypopharyngeal SCC versus cervical oesophageal SCC D. Gujral 1 , S.Y. Lim 1 , W. Park 1 1 Imperial College Healthcare NHS Trust, Department of Clinical Oncology, London, United Kingdom Purpose or Objective The hypopharynx and cervical oesophagus are in adjacent anatomical locations, yet squamous cell carcinomas (SCC) in these subsites are managed with different treatment regimens. We investigated survival outcomes for both groups where patients had junctional tumours overlapping both subsites. Materials and Methods We retrospectively reviewed consecutive patients diagnosed with hypopharyngeal or cervical oesophageal SCC at a single institution managed either by a head and neck or upper gastrointestinal multidisciplinary team, respectively. Patients with earlier stage hypopharynx SCC were managed with primary radiotherapy (RT) or chemoradiotherapy (CRT) (with or without induction chemotherapy (IC)) to doses of at least 65 Gy/30# over 6 weeks, whereas patients with locally advanced cancer and functional impairment were managed with primary surgery (Sx) and post-operative RT/CRT to doses of at least 60 Gy/30# over 6 weeks. Patients with cervical oesophagus SCC were managed primarily with IC followed by RT or CRT, with RT doses of 50-54 Gy in 25- 30# over 5-6 weeks. IC and/or concurrent chemo was platinum-based for both groups. Treatment response was assessed at around 12-16 weeks post-treatment using CT or PET-CT scan. Survival was assessed as time to recurrence or death from completion of treatment. Results Between 01/2013 and 12/2019, we identified 42 patients. Of these, 15 were excluded due to metastatic disease (N=11) or unfit for curative therapy (N=3/9 (33%) for oesophagus; N=1/22 (4.5%) for hypopharynx). Therefore, 27 patients (21 hypopharynx, 6 oesophagus) with stage I – IVb SCC were included in this study. Median (interquartile range) follow up was 22 (15-64) months for hypopharynx and 40 (24-51) months for oesophagus. 13/27 (62%) of hypopharynx achieved complete response to treatment versus 2/6 (33%) for oesophagus. 8/21 (38.1%) received salvage treatment after relapse (RT/CRT or Sx) in the hypopharynx group versus 1/6 (33%) in the oesophagus group (Sx+RT). There was no significant difference in survival outcomes between the 2 groups: median disease-free survival was 15 months for hypopharynx vs 45 months for oesophagus(p=0.44) and median overall survival was 55 months for hypopharynx vs 81 months for oesophagus (p=0.73). Conclusion A higher rate of complete response to treatment in the hypopharyngeal SCC group did not translate into superior survival outcomes compared to oesophageal SCC. This should be investigated further in a prospective setting to determine (i) if better selection of patients for curative treatment affects overall survival, (ii) the effect of salvage therapy on survival, and (iii) whether there is an advantage of smaller radiation fields and doses used to treat oesophageal SCC in terms of long-term toxicities. PO-0965 Vitamin D, vitamin B12 and acute toxicity in head and neck cancer patients undergoing radiotherapy. G. Fanetti 1 , J. Polesel 2 , F. Matrone 1 , I. Turturici 1 , C. Gobitti 1 , S. Alfieri 3 , V. Lupato 4 , F.B. La Torre 4 , E. Fratta 5 , E. Muraro 5 , M.T. Casarotto 5 , R. Guerrieri 5 , V. Giacomarra 4 , A. Steffan 5 , E. Vaccher 3 , G. Franchin 1 1 Centro di Riferimento Oncologico di Aviano (CRO) IRCCS, Division of Radiation Oncology, Aviano, Italy; 2 Centro di Riferimento Oncologico di Aviano (CRO) IRCCS, Unit of Cancer Epidemiology, Aviano, Italy; 3 Centro di Riferimento Oncologico di Aviano (CRO) IRCCS, Division of Medical Oncology and Immune-related Tumors, Aviano, Italy; 4 "Santa Maria degli Angeli" General Hospital, Division of Otolaryngology, Pordenone, Italy; 5 Centro di Riferimento Oncologico di Aviano (CRO) IRCCS, Division of Immunopathology and Cancer Biomarkers, Aviano, Italy Purpose or Objective In recent years there has been a growing interest in defining the properties of vitamin D (VitD) in several fields of medicine. Vit D has emerged as part of patients’ nutritional status, and lower levels of circulating VitD have been associated with increased risk of cancer, in particular Head and Neck cancer (HNCa). Few reports underline an increased risk of death and treatment induced toxicity in HNCa patients with lower levels of VitD. Similarly, vitamin B12 (VitB12) is considered an indicator of nutrition status, and its role during radiotherapy (RT) is unclear. The aim of the present study is to investigate whether baseline levels of serum VitD and VitB12 are associated to acute toxicity during radiotherapy. Materials and Methods We conducted a retrospective analysis of 102 HNCa patients treated at Centro di Riferimento Oncologico di Aviano (CRO) IRCCS between March 2019 and January 2021. Inclusion criteria included the evaluation of serum VitD and VitB12 at baseline, HNCa of all subsites, indication to radical or adjuvant RT with high-risk Planning Treatment Volume receiving 66-70 Gy, no discontinuation of the RT. Serum VitD level was defined as normal