282P Three decades of experience in squamous thymic carcinoma: Treatment outcomes and challenges in a rare malignancy

Background: Squamouscell thymic carcinoma (SQ-TC) is characterised by a very low incidence rate.This study aimed to describe the clinical characteristics of patients with this rare diagnosis, and to summarise the therapeutic strategies and treatment results in daily practice.Methods: This is a retrospective, single-centre analysis of patients who were eligible for treatment at the National Institute of Oncology in Warsaw between 1995 and 2024.Results: The analysis included 70 patients, 58% of whom were male.In 39% of patients SQ-TC was diagnosed at CS IV according to TNM.Palliative chemotherapy was the most common primary treatment for the entire population (40%), while surgical treatment was performed in 30% of patients (R0 in 21% of patients).In other pts, radical chemoradiotherapy (21%) or palliative radiotherapy (9%) was performed.After a median follow-up time of 33.9 months, the mPFS was 16.5 months (95% CI 12.5-31.5),and mOS -41.3 months (95% CI 28.5-61.2) in the entire population, with death recorded in 74% of pts.The significant prognostic value of T component for PFS and OS was demonstrated in analysed population -data related to OS are presented in the Table .Additionally, patients in CS IV had significant shorter PFS (53.9 vs. 8.5 months, p < 0.001) and OS (59.2 vs. 22.1 months, p = 0.003).In the entire population, disease spread (primary or secondary) was documented in 51 pts.Of these pts, 45 received systemic treatment, OS was longer in pts who received two or more lines of systemic therapy (p=0.01).Due to reimbursement restrictions, only six pts received immunotherapy and two pts received a tyrosine kinase inhibitor.