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8555 Background: Pulmonary sarcomatoid carcinoma (PSC) is a rare subtype of non-small cell lung cancer (NSCLC), with historically poor outcome. Excellent response of metastatic PSC to immunotherapy was previously reported, but its outcome compared with other NSCLCs is unknown in the immunotherapy era. Methods: NCDB was queried for stage IV NSCLC diagnosed from 2016 to 2020. Patients who were treated with chemotherapy only or immunotherapy only in the first course of treatment were included. Log-rank was used for survival analysis and adjusted by cox regression for age, gender, race, academic/integrated center, insurance, and comorbidity. Results: A total of 37,617 patients were identified, including 201 PSCs and 37,416 other NSCLCs. Pleomorphic (54%) was the most common PSC subtype. There was significant interaction between the survival effect of treatment and histology (interaction p = 0.024). When treated with immunotherapy alone, no significant difference was found between PSC and other NSCLCs (median survival 11.4 vs 12.4 months, logrank p = 0.56, HR 1.02, 95% CI 0.81 – 1.30). However, when treated with chemotherapy alone, PSC remained significantly associated with worse survival (median survival 4.5 vs. 8.5 months, logrank p <0.001, HR 0.67, 95% CI 0.54 – 0.83). Among PSC subtypes, spindle/giant cell PSCs were more likely to benefit from immunotherapy alone than pleomorphic PSCs (interaction p = 0.005), when compared with chemotherapy (Spindle/giant cell subtype: HR 0.24, 95% CI 0.14 – 0.42; Pleomorphic subtype: HR 0.60, 95% CI 0.37 – 0.99). Conclusions: Compared with other NSCLCs, PSC may not be associated with worse survival when treated with immunotherapy alone as it was when treated with chemotherapy. Distinct PSC subtypes may respond differently to immunotherapy and warrants further research. Table: see text
Liu et al. (Sat,) studied this question.