Prognostic factors after treatment for iterative thymoma recurrences: A multicentric experience

Thymomas are rare neoplasms with a low recurrence rate, which are preferably surgically treated. Iterative thymoma surgery has not been well investigated yet. Study aim is to analyse prognostic factors after iterative recurrence treatment.

Clinical, pathological and surgical findings of 155 patients, treated for thymoma recurrence in three high-volume centres from 01/01/1990 to 1/07/2017, were retrospectively reviewed. Recurrence patterns/treatment types (surgery or chemotherapy, radiotherapy or combined) were correlated to overall (OS) and disease free survival (DFS).

Myasthenia Gravis was present in 135 (87%) patients. Surgery was performed in 135/155 (87%) patients with 109 (80.7%) complete resections. Sixty (55%)patients experienced a second recurrence surgically treated in 31/60 (52%) cases with 18 (58%) complete resections. Eleven (61%) patients experienced a third recurrence and nine underwent complete resection. Myastenia Gravis (HR: 0.45; 95% CI: 0.20-0.98, p = 0.046), DFS after the initial thymectomy >36 months (HR: 0.9; 95% CI: 0.96-0.99, p = 0.006) and complete second recurrence resection (HR: 1.45; 95% CI 2.07-10.01, p = 0.010) resulted as independent favorable prognostic survival factor. Despite patient selection bias, rewarding long-term survivals was predictable after iterative thymoma surgery (5 and 10 years survival of 79.6% and 64.6%) while a poor prognosis was observed after CT/RT (5 and 10 years OS of 56.7% and 21.5%), Masaoka stage and DFS > 36 months were risk factor for iterative recurrences.

Myasthenia Gravis and long DFS after thymectomy are favorable survival factors for multiple thymoma recurrences. Iterative surgical treatment is a viable therapeutic option associated to long-term survival if technically and clinically feasible.