Thymoma: prognostic factors

The relative importance of factors influencing prognosis and survival in the treatment of thymoma is still controversial. Fifty-three patients operated on for thymoma from 1966 to 1990 were evaluated, 14 with myasthenia gravis and 39 without. Survival was analyzed as it related to associated disease, gross invasion by the tumor and the predominant cell type. Follow-up information was obtained in all cases (mean observation time: 11.2 years). A high proportion (51%) of our patients had invasive forms (stages III and IV). The overall 5-, 10- and 20-year survival rates were 52%, 46% and 21%, respectively. Factors indicating a poor prognosis included local invasion (P < 0.0001), predominantly, epithelial histologic features (P = 0.002), tumor-related symptoms and the type of surgical procedure. Myasthenia gravis was not an adverse factor for survival. The degree of tumor invasion was the main prognostic factor and treatment should be planned accordingly.