Long-term, disease-specific outcomes of thymic malignancies presenting with de novo pleural metastasis

Objective: Treatment of patients with thymic malignancies metastatic to the pleura or pericardium is challenging, and benefits of aggressive treatment are unclear. We sought to characterize the long-term outcomes in this population. Methods: We retrospectively identified patients who underwent resection for de novo thymic malignancies metastatic to the pleura between May 1997 and December 2017. Patients with pleural recurrence after prior thymectomy were excluded. Patient demographics, perioperative treatments, pathologic findings, and postoperative outcomes were collected. Descriptive statistics and Kaplan-Meier analyses were performed. Results: Seventy-two patients were included (median age, 51 years [range 25-80]; 36/72 women [50%]). Pathologic diagnosis was thymoma in 57 patients (79%) and thymic carcinoma in 15 patients (21%). Most patients (67/72; 93%) received chemotherapy, radiation, or both. Forty-eight patients underwent thymectomy with pleurectomy, 7 patients underwent extrapleural pneumonectomy, 10 patients underwent thymectomy alone, and 7 patients were unresectable. Macroscopic complete resection was achieved in 52 patients (73%). Five-, 10-, and 15-year overall survivals were 73%, 51%, and 18%, respectively, and median overall survival was 11 years (median follow-up, 5.9 years). Forty-six patients (64%) had disease progression (median time to progression, 2.2 years). Repeat episodes of progression and treatment were common (median, 3 episodes/patient). The longest disease-free interval was 12.4 years. Thirteen patients (18%) remain disease-free; 7 patients (10%) were disease-free for more than 5 years. The longest ongoing survival without progression or reintervention is 9.9 years. Conclusions: Prolonged survival and, in some cases, cure can be achieved in patients with thymic malignancies metastatic to the pleura or pericardium. Aggressive multimodality therapy may be appropriate for select patients.