Long-term survival and prognostic factors in thymic epithelial tumours

The aim of this study is to analyze long-term survival and the prognostic significance of some factors after surgical resection of thymic epithelial tumours.

We performed a retrospective analysis of clinical and histopathological data on 132 patients operated on for thymic tumours, from 1970 and 2001. Histologic diagnosis based on the new WHO classification system was made by a single pathologist. A univariate and multivariate analysis of prognostic factors predicting survival was carried out.

There were: 108 complete resections (81.8%), 12 partial resections (9.1%) and 12 biopsies (9.1%). Overall 5, 10 and 15-year survival rate was 72, 61 and 52.5%, respectively. The Masaoka staging system showed 44 stage I, 18 stage II, 52 stage III and 18 stage IV. Histologic results were: 14 subtype A, 31 AB, 20 B1, 28 B2, 29 B3 and 10 C; the respective proportions of invasive tumour (stage II-IV) was 28.6, 58.1, 50, 75, 86.2 and 100%. There were 16 tumour recurrences (14.8%) of 108 radically resected thymomas, 10 were treated with radical re-resection. In univariate analysis, four prognostic factors were statistically significant: radical resection, Masaoka clinical staging, WHO histologic subtype and resectable tumour recurrence. In multivariate analysis, the independent factors predicting long-term survival were WHO histology and Masaoka stage.

The WHO histologic classification seems to be the most significant prognostic factor reflecting the invasiveness of the thymic tumour. Completeness of resection and Masaoka stage I and II assure a better survival. Unresectable recurrence of thymic tumour predicted a worse prognosis.