Comparison of clinical outcomes in patients with advanced pulmonary sarcomatoid carcinoma treated with immunotherapy-based regimen or chemotherapy: A study based on the SEER database and multicentric real-world settings

e20573 Background: Pulmonary sarcomatoid carcinoma (PSC) is a rare pulmonary cancer characterised by early metastasis and invasion, predominantly diagnosed with locally advanced or metastasis, hindering the possibility of surgical intervention. However, a standardised treatment strategy for advanced PSC is yet to be established. Herein, we aimed to evaluate the effects of immunotherapy-based strategies or chemotherapy on patients with advanced PSC. Methods: We conducted a retrospective study to compare the clinical outcomes of immunotherapy-based regimens and chemotherapy in patients with advanced PSC using the Surveillance, Epidemiology, and End Results (SEER) database and data from three cancer centres. Progression-free survival (PFS) and overall survival (OS) were calculated using the Kaplan–Meier method. Univariate and multivariate analyses were performed to identify prognostic factors. Results: In total, 202 patients with stage IV PSC were identified from the SEER database. The median OS was 5 months. The median follow-up time of PSC patients from three cancer centres was 27.5 months Considering all three cancer centres, first-line treatment with a first-line immunotherapy-based regimen and chemotherapy were administered to 12 and 16 patients, respectively. The median PFS was 2.1 (95% confidence interval [CI] [2.1, 4.1]) and 7.2 (95% CI [6.8, 7.6]) months for the chemotherapy- and immune-based groups, respectively (p < 0.001). The median OS was 3.6 (95% CI [1.6, 5.6]) and 13.7 (95% CI [5.1, 22.3]) months for the chemotherapy and immune-based groups, respectively (p = 0.003). Multivariate analysis revealed that the immunotherapy-based regimen was an independent prognostic factor for PFS and OS (p < 0.01, hazard ratio [HR] = 0.22, 95% CI [0.07,0.67] and p < 0.01 HR = 0.27 95% CI [0.11,0.68], respectively). Conclusions: Conventional chemotherapy has limited benefits in patients with stage IV PSC. However, patients with advanced PSC who received first-line immunotherapy-based regimens exhibited a remarkable response. The immunotherapy-based regimen was an independent prognostic factor for PFS and OS.