Thymic carcinoma: involvement of great vessels indicates poor prognosis

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

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.

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).

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.