Clinical and pathologic predictors of survival in patients with thymic tumors

The aim of this study is to evaluate the impact of thymectomy in patients with thymic neoplasms and to identify clinical and histopathological factors associated with improved long-term outcome of surgery.

We treated 74 patients between February 1987 and July 1993. There were 29 total and 36 simple thymectomies. These last cases, all non-myasthenic, had benign thymomas (n=30) but 6 had thymic carcinomas. Nine tumors were no-resected (5 thymomas and 4 thymic carcinomas). Minimum follow-up by Department of Thoracic Surgery Istituto Nazionale Tumori was 60 months after thymectomy. We divided the specimens according to Marino and Muller-Hermelink's classification: 54 thymomas, 18 thymic carcinomas and 2 no-diagnosis specify thymomas. There were 53 stage I, 1 stage II, 13 stage III, 5 stage IVa and 2 stage IVb according to Masaoka.

Forty-six patients with treated thymoma were alive without disease at the end of follow-up, the remaining 8 died from recurrence in 6, a new tumor in 1 and a heart attack in the last. Of 18 thymic carcinomas 9 were alive at the end of follow-up (1 with recurrence), only 4 dead from recurrence. The actuarial survival of patients with thymomas was 88.5% at 5 years, (73.6% in cortical type, 85.7% in medullary type, 93.9% in mixed type, 100% in predominantly cortical type). Myasthenia gravis didn't influence the survival: 87.3 (no MG) vs 90%. Advanced stage thymomas significantly increased the risk of death from early stage I: 32.4 vs 100% at 5 years. In thymic carcinoma patients with well-differentiated thymic carcinoma (WDTC) died less than others: the actuarial probability of survival at 5 years was 90 vs 68%.

Thymectomy was the best treatment to long term outcome. In our experience, survival was related to histotype and to local extension of tumor.