Clinical features and prognosis of primary tracheal small cell carcinoma: a population-based analysis

Background: Primary tracheal small cell carcinoma (SCC) is an uncommon malignancy; therefore, its clinical features and prognosis are still unclear. Methods: We used the population-based Surveillance, Epidemiology, and End Results (SEER) database to elucidate the clinical features and prognosis of primary tracheal SCC. The clinical features were assessed by using the chi-square test. Overall survival (OS) was computed using the Kaplan-Meier method, and a Cox proportional hazards analysis was performed to evaluate the prognostic factors. Results: From 1973 to 2015, 1,392 primary tracheal tumor cases were reported in the SEER database, 75 (5.4%) of which were SCC. Age, sex, race, extent of disease, lymph node involvement, surgery and radiation treatment were similar between patients with SCC and those with squamous cell carcinoma (SQC), but patients with SCC were more likely to receive chemotherapy (65.8% vs. 28.2%, respectively; P<0.001). The 1-, 3- and 5-year OS rates of patients with SCC were 37.8%, 12.4% and 7.1%, respectively, and the median survival duration was 10.0 months, which was much worse than that observed for patients with other histopathological types of tracheal cancer. Among patients aged 60-100 years and those with regional lymph node involvement, the OS for patients with SQC was superior to that for patients with SCC (P=0.034 and P=0.016, respectively). According to the multivariate analysis, age and lymph node involvement are independent prognostic factors of SCC. Conclusion: Primary tracheal SCC is a rare carcinoma with a poor prognosis. Age and lymph node involvement are independent prognostic factors of SCC.