Preoperative systemic immune-inflammation index predicts survival and recurrence in patients with resected primary pulmonary sarcomatoid carcinoma

Background Pulmonary sarcomatoid carcinoma (PSC) is a rare lung cancer subtype. Studies concerning PSC are limited and controversial; therefore, we analyzed the treatment and outcomes of PSC utilizing a relatively large single-institution database. Methods From January 2003 to December 2018, 262 consecutive PSC patients treated at our institution were retrospectively reviewed. The clinical characteristics, treatments, and outcomes were analyzed. Results The median survival time (MST) was 22.0 months, with 1-, 3-, and 5-year overall survival (OS) rates of 59.9%, 40.1%, and 36.1%, respectively. Patients who underwent surgery had a significantly better prognosis than patients who received nonsurgical treatment (MST, 23.0 vs. 11.0 months, P=0.016). The use of surgery followed by adjuvant therapy significantly prolonged survival in stage III patients (MST, 17.0 vs. 8.0 months, P=0.003) but not in stage I and II patients. Multivariate analysis showed that a systemic inflammation-immune index (SII) value >430.8, TNM stage and necrosis were independent prognostic predictors of OS and disease-free survival (DFS) in radically resected PSC patients (P<0.05). In addition, SII and necrosis were independent risk factors for recurrence after the radical resection of PSC (P<0.05). Conclusions PSC is aggressive and has a poor prognosis. Surgery should be the mainstay treatment for operable cases, and adjuvant therapy is recommended for locally advanced disease. A novel potential biomarker, SII, which is an integrated parameter based on preoperative lymphocyte, neutrophil, and platelet counts, may be useful for prognostic prediction and the identification of resected PSC patients at high risk for recurrence.