OBJECTIVES: Cytoreductive surgery and hyperthermic intrathoracic chemotherapy (HITOC) is effective on survival for patients with pleural metastatic thymic tumours.METHODS: Multicentre, 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.RESULTS: A total of n = 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 in n = 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/m(2) body surface area. Surgical revision was required in 8 (14%) patients. In-hospital mortality rate was 2%. During follow-up, tumour recurrence/progression was evident in n = 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).CONCLUSIONS: Promising 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.