Identification of predictors of long-term survival and prognostic outcomes in thymic squamous cell carcinoma: A real-world study

Abstract

Background: Although thymic squamous cell carcinoma (TSCC) is among the most prevalent forms of thymic carcinoma, there are relatively few studies on this tumor type, and its staging, optimal treatment strategies, and relevant prognostic factors remain controversial.

Methods: The present study analyzed 79 patients diagnosed with TSCC between January 2008 and January 2021. Kaplan-Meier curves and Cox univariate and multivariate regression analyses were used to explore factors associated with overall survival (OS) and progression-free survival (PFS) in the overall patient cohort and patient subgroups stratified according to the TNM stage. Time-dependent receiver operating characteristic (ROC) analyses were used to compare the TNM and Masaoka systems as predictors of patient prognosis.

Results: The 5- and 10-year OS rates in this study were 65.5% and 49.4%, respectively, with corresponding 5- and 10-year PFS rates of 52.3% and 37.9%. Survival outcomes were better for patients with early-stage disease (p < 0.001) and patients that underwent surgical treatment (p < 0.001). Neither extent of resection (p = 0.820) nor the surgical approach (p = 0.444) influenced patient survival. In individuals with advanced disease, all forms of adjuvant therapy including radiotherapy (p = 0.021), chemotherapy (p = 0.035), and chemoradiation (p = 0.01) significantly improved patient PFS, but only adjuvant chemoradiotherapy improved patient OS (p = 0.035). When predicting the patient survival outcomes, the TNM system was slightly superior to the Masaoka system (area under the ROC curve [AUC] at 5 years: OS, 0.742 vs. 0.723; PFS, 0.846 vs. 0.816).

Conclusion: TSCC is an orphan malignancy with a poor prognosis. TNM staging may be superior to Masaoka staging as a predictor of TSCC patient prognosis. Surgery is the mainstay of TSCC treatment. Video-assisted thoracoscopy (VATS) should be considered for selected patients. Multimodal therapy was associated with excellent results for patients with advanced TNM stage, particularly when surgery was accompanied by adjuvant chemoradiation.

Keywords: TNM system; chemoradiotherapy; surgery; thymic squamous cell carcinoma.