Surgery in Masaoka stage IV thymic carcinoma: a propensity-matched study based on the SEER database.

backgroundThymic carcinoma is a type of rare and highly malignant tumor. Limited information was available on prognostic factors of late-stage thymic carcinoma. The aim of this study was to identify factors that impact prognosis and to define the relationship between survival and surgical intervention in patients with Masaoka stage IV thymic carcinoma.

methodsFrom 1973 to 2015, a total of 311 consecutive patients were enrolled in this study with pathologic confirmed Masaoka stage IV thymic carcinoma from the Surveillance, Epidemiology, and End Results database. Kaplan-Meier analyses, Cox-regression analyses and propensity score matching (PSM) were performed to evaluate prognosis.

resultsIn the multivariate analysis, larger tumor size, distant metastasis and positive lymph node status were associated with poorer outcome. After PSM, no receipt of surgery was the prognostic factor indicating poorer survival [hazard ratio (HR) 1.985, 95% confidence interval (CI) 1.007-3.913, P=0.048 for overall survival (OS); HR 1.649, 95% CI: 1.009-2.697, P=0.046 for disease-specific survival (DSS)]. Subgroup analysis indicated that significantly improved survival with surgery was observed in patients who were <60 years (HR 0.48, 95% CI: 0.32-0.72), female (HR 0.37, 95% CI: 0.23-0.60), Caucasian (HR 0.56, 95% CI: 0.40-0.77), with larger tumor size (≥7.0 cm, HR 0.42, 95% CI: 0.25-0.69), with (HR 0.60, 95% CI: 0.39-0.90) or without distant metastasis (HR 0.46, 95% CI: 0.26-0.83), and node-positive (HR 0.56, 95% CI: 0.38-0.82).

conclusionsSurgical treatment could be beneficial in patients with Masaoka stage IV thymic carcinoma. This SEER based analysis revealed the role of surgical resection and the favorable effect of surgery in specific thymic carcinoma subgroups.