ESTRO 2023 - Abstract Book

S297

Sunday 14 May 2023

ESTRO 2023

a strong return on the investment. This study indicates that contouring accuracy exercises could be integrated into RTT IGRT training now to build RTT skills and experience in preparation for OART.

Poster Discussion: Head & neck

PD-0395 Management of 80 Sinonasal Undifferentiated Carcinomas. A french retrospective multicentre study P. Pouvreau 1 , J. Coelho 2 , C. Rumeau 3 , O. Malard 4 , R. Garrel 5 , J. Thariat 6 , N. Vulquin 7 , C. Castain 8 , L. de Gabory 9 , C. Dupin 1 1 Bordeaux University Hospital, Department of Radiation Oncology, Bordeaux, France; 2 Bordeaux university, SANPSY unit, UMR 6033, Bordeaux, France; 3 Nancy University Hospital, Department of Head and Neck Surgery, Nancy, France; 4 Nantes University Hospital, Department of Head and Neck Surgery, Nantes, France; 5 Montpellier University Hospital, Department of Head and Neck Surgery, Montpellier, France; 6 François Baclesse center, Department of Radiation Oncology, Caen, France; 7 Georges François Leclerc Center, Department of Radiation Oncology, Dijon, France; 8 Bordeaux University Hospital, Department of histopathology, Bordeaux, France; 9 Bordeaux University Hospital, Department of Head and Neck Surgery, Bordeaux, France Purpose or Objective Sinonasal undifferentiated carcinoma (SNUC) is a rare and aggressive disease requiring multimodal treatment, and multiple new entities once included in the spectrum of SNUC, such as SWI/SNF-deficient carcinomas, are emerging. We aimed to provide new data regarding the role of chemotherapy and surgery and the prognostic factors of disease-free survival. Materials and Methods This study was based on data from the French Network of Rare Head and Neck Cancers database (REFCOR), and included patients with SNUC treated with curative intent from 2007 to 2021 across 22 centres in France. We collected data on treatments, histologic and oncologic outcomes, toxicities and prognostic factors. Results A total of 80 patients were included in the analysis. Among the entire cohort, the 5-year progression-free survival (PFS) and overall survival (OS) rates were 58% and 63%, respectively. Approximately 100% of the patients were treated with irradiation, 29% with surgery, 56% with neoadjuvant chemotherapy (82% had either a partial or a complete response) and 76% with chemoradiotherapy. No treatment modality was associated with a better OS or PFS, including surgery (p=0.34). There was a trend for a better PFS for the patients treated with chemotherapy (neoadjuvant or concurrent, p=0.062). The patients with SWI/SNF-deficient carcinomas had a significantly worse PFS (p=0.021) and OS (p=0.03) than the rest of the population. Conclusion In the management of localised SNUC among all patients treated with irradiation, surgery yielded no benefit, whereas the addition of chemotherapy tended to improve disease-free survival. PD-0396 Novel Enhancement of Pulsing involved-field Radiotherapy and CPI for LAHNSCC in elderly patients. A. Raben 1 , O. Russial 2 , S. Park 3 , N. Hockstein 4 1 Christiana Care Health System, Radiation Oncology, Newark, USA; 2 Thomas Jefferson University Hospital, Radiation Oncology, Philadelphia, USA; 3 Christiana Care Health System, Medical Oncology, Newark, USA; 4 Christiana Care Health System, ENT, Newark, USA Purpose or Objective Purpose: To combine pulsing RT schedule (QUAD shot) directed only to gross HNSCC to enhance response to immunotherapy in elderly patient’s ineligible for conventional RT approaches. Materials and Methods Materials/Method: 23 Patients, with a mean age 82, were evaluated in an MDC-HN clinic with non-metastatic either recurrent or unresectable cutaneus SCC (cSCCC) or mucosal SCC (mSCC), 21/23 were HPV- , 52% Male, 48% Female. These patients were prohibitive candidates for curative ERT +/- chemotherapy due to age, Poor KPS or ECOG PS, or co-morbidities. Patients were treated with a pulsed recurring ERT schedule (QUAD SHOT) using VMAT , delivering 14.8 Gy/4 fxs/BID, repeated q 3 weeks. Based on imaging, ONLY Gross Primary/LN’s were treated, while END were excluded. PD-1 CPI’s were administered either day 2 of the QUAD shot or day 1-3 after each QUAD shot. (either Pembrolizumab, Cemilipumab, Nivolumab) and continued adjuvantly at the discretion of the Medical Oncologist. Patients were evaluated at conclusion of QUAD Shots for response and at 3 months with PET/CT and then till death. Primary endpoint for this study: LRC and RC-END (elective LNs not treated) Secondary endpoints: DMFS, DFS. Results Results: With a median FU of 17 mos (1-39 mos) 72% of pts (16/22) achieved a CR based on clinical and radiologic evaluation, with 22% achieving a PR. 1 pt showed POD, and 1 not evaluable due to Covid death. The KM overall LRC estimate at 1 year was 78%. The KM LRC-END estimate at 1 year was 93% (untreated elective LN’s). The KM DM rate estimate at 1 year was 85%. The KM curve estimate for overall DFS at 1 year was 59% (67% cSCC, 55% mSCC) LRC for gross recurrent/unresectable/regional parotid/nodal cSCC was especially encouraging with QUAD+CPI with a 1 year KM rate of 100% versus 70% for mucosal SCC (p=.17). KM LRC-END estimate at 1 year for cSCC versus mSCC was 100% versus 91% (p=.27) DM estimate at 1 year for cSCC was 100% versus 79@ mSCC. The combined QUAD SHOT schedule was well tolerated when combined with a CPI, with only 1/23 pts requiring treatment interruption and admission for FTT (Failure to Thrive) but resumed and completed therapy. Gr 3 mucositis occurred in 1 pt on the lower lip that resolved. Gr 1 fatigue, xerostomia, and anorexia were noted in 1 patient. Gr 3/ 4 IMAR’s were observed in 3 patients and included infusion reaction, colitis, and fatigue/FTT and were discontinued. 4 pts (23%) required post QUAD PEG’s unrelated to radiation toxicity and due to POD.