AbstractOBJECTIVESCytoreductive surgery and hyperthermic intrathoracic chemotherapy (HITOC) is effective on survival for patients with pleural metastatic thymic tumours.METHODSMulticentre, retrospective analysis of patients with stage IVa thymic tumours treated with surgical resection and HITOC. Primary end point was overall survival, secondary end points were recurrence-/progression-free survival and morbidity/mortality.RESULTSA total ofn= 58 patients (thymoma,n= 42; thymic carcinoma,n= 15; atypical carcinoid of the thymus,n= 1) were included, who had primary pleural metastases (n= 50; 86%) or pleural recurrence (n= 8; 14%). Lung-preserving resection (n= 56; 97%) was the preferred approach. Macroscopically complete tumour resection was achieved inn= 49 patients (85%). HITOC was performed with cisplatin alone (n= 38; 66%) or in combination with doxorubicin (n= 20; 34%). Almost half of the patients (n= 28; 48%) received high-dose cisplatin > 125 mg/m2body surface area. Surgical revision was required in 8 (14%) patients. In-hospital mortality rate was 2%. During follow-up, tumour recurrence/progression was evident inn= 31 (53%) patients. Median follow-up time was 59 months. The 1-, 3- and 5-year survival rates were 95%, 83% and 77%, respectively. Recurrence/progression-free survival rates were 89%, 54% and 44%, respectively. Patients with thymoma had significantly better survival compared to patients with thymic carcinoma (P-value ≤0.001).CONCLUSIONSPromising survival rates in patients with pleural metastatic stage IVa in thymoma (94%) and even in thymic carcinoma (41%) were achieved. Surgical resection and HITOC is safe and effective for treatment of patients with pleural metastatic thymic tumours stage IVa.