Thymic carcinoma: involvement of great vessels indicates poor prognosis

Abstract

Background: Thymic carcinoma is a rare, indolent, and invasive cancer. This study investigated the treatment results of thymic carcinoma and clinical prognostic factors.

Methods: From June 1988 to January 2002, 38 patients were enrolled in this study with the diagnosis of thymic carcinoma in the Cheng-Kung University Hospital based on Rosai's and Muller-Hermelink's classification. Clinical and pathologic data were retrospectively reviewed. Survival analysis was performed using the Kaplan-Meier, log rank, and Wilcoxon tests. Statistical significance was defined as p < 0.05.

Results: Pathology revealed 14 poorly differentiated, 6 moderately differentiated, and 8 well-differentiated squamous cell carcinomas; 8 lymphoepithelioma-like carcinomas; and 2 other carcinomas. Pathologic staging using the Masaoka system included 6 stage II, 23 stage III, and 9 stage IV patients. Six biopsies, five debulkings, and 27 complete resections were performed. All patients were followed from 15 months to 10 years 9 months, with an average of 53.8 months. Median survival time was 81 months, and median recurrence time was 52 months. Eighteen patients are still alive, and 7 are alive with disease. Well-differentiated squamous cell carcinoma had better prognosis than other carcinomas (p = 0.022). Complete resection significantly increased survival rate (p < 0.001). Tumor invasion of the superior vena cava, pulmonary vessels, or aorta were significant predictors for poor prognosis (p = 0.016, 0.002, and 0.002, respectively).

Conclusions: Only patients with thymic carcinoma who underwent complete resection had long-term survival. Prognosis of thymic carcinoma seemed mainly dependent on tumor invasion of the great vessels.