ESTRO 2023 - Abstract Book

S298

Sunday 14 May 2023

ESTRO 2023

Conclusion Conclusions: This feasibility study, is one of the first utilizing a pulsing radiotherapy in elderly patients with LAHNSCC combined with a CPI. This regimen was well tolerated with very encouraging response LRC at 1 year. More encouraging, was the lack of significant END failure suggesting that this may be excluded from treatment particularly in elderly patients with cSCC. This unique approach is a potential means to release neoantigens, prime the TME and evolve away from ENI that engender greater toxicity and cost. PD-0397 Clinical outcome of lung-only oligometastatic HNSCC patients treated with SBRT: Update results V. Salvestrini 1 , I. Bonaparte 2 , N. Bertini 3 , C. Mattioli 3 , C. Bellini 3 , C. Becherini 3 , I. Desideri 3 , P. Garlatti 3 , M. Banini 3 , L. Zisca 3 , L. Livi 3 , P. Bonomo 3 1 CyberKnife Center, Istituto Fiorentino di Cura ed Assistenza, Radiation Oncology, Florence, Italy; 2 Azienda Ospedaliero Universitaria Careggi, University of Florence, Radiation Oncology, Florence, Italy; 3 Azienda Ospedaliero-Universitaria Careggi; University of Florence, Radiation Oncology, Florence, Italy Purpose or Objective Oligometastatic disease in head and neck squamous cell carcinoma (HNSCC) is an atypical scenario. Local ablative treatments are the most adopted strategies although no evidence-based recommendations are currently available. The purpose of our analysis was to update and report on long-term clinical outcomes of a cohort of HNSCC patients treated with stereotactic body radiotherapy (SBRT) for lung-only oligometastatic disease. Materials and Methods We included patients with 1 to 5 pulmonary lesions. The oligometastatic pattern was defined as “de novo” (suitable for SBRT only) or “oligoprogressive” (after first line of systemic therapy). We evaluated time to progression (TTP) as the time from the last day of SBRT to disease progression or death from any cause. Predictive factors of better clinical outcome and survival analysis were performed by Cox regression and Kaplan Meier methods, respectively. Results A cohort of 47 patients and 48 metastases were retrospectively evaluated (Table 1). The median age was 67 years (range 37-86) and 87% of patients had a ECOG PS 0-1. HPV negative status (77%) and “de novo” oligometastatic pattern (78%) were reported by the majority of patients. After a median follow up of 28 months (range 2-88), median TTP and overall survival (OS) were 18 months (95% CI 4.8 – 31.2) and 62 months (95%CI 10,8 - 113.2), respectively (Figure 1). At univariate analysis, patients aged > 70 years reported a better TTP (p 0.013). No statistically significant correlation was observed in respect with gender (p 0.23), ECOG PS (p 0.34), oligometastatic pattern (p 0.13) and p16/HPV status (p 0.22). Out of 26 histologically proven metastases, we collected only 2 patients reporting concordance between p16/HPV positive status of primary tumor and lung metastases. Overall, 6 patients reported grade (G) 1-2 acute toxicity and no acute G3 adverse events were observed.