Comparison of surgical approach and extent of resection for Masaoka-Koga Stage I and II thymic tumours in Europe, North America and Asia: an International Thymic Malignancy Interest Group retrospective database analysis†

Abstract

OBJECTIVES: Surgeons at different institutions worldwide choose different types of operations for thymic tumours. It is not known whether these differences affect the outcomes of the patients. METHODS: A total of 1430 patients with Masaoka-Koga pathological Stage I-II thymic tumours without myasthenia gravis or pre-treatment were identified from the International Thymic Malignancy Interest Group retrospective database. Outcomes of patients from 3 major continents (Europe, North America and Asia) were compared. RESULTS: Patients from the 3 continents were comparable in gender and performance status. More European patients had more paraneoplastic syndromes; North American patients had the smallest tumour sizes and less adjuvant therapy; and Asian patients were younger and had more Stage I disease but higher grade tumours. Partial thymectomy was performed more often in Asian patients (31.7%) than in European (2.4%) and North American (5.4%; P < 0.001) patients. The median approach (sternotomy/clamshell) was the major approach in Europe (75.3%) and North America (76.6%). In contrast, the median approach was applied significantly less frequently in Asia (45.6%, P < 0.001); unilateral open (thoracotomy/hemi-clamshell, 23.3%) and minimally invasive approaches (video-assisted thoracoscopic surgery/robot, 31.1%) were used more often with similar rates of complete resection. The 10-year overall survival rate was 82% for Europe, 78% for North America and 90% for Asia ( P = 0.005), respectively. The 10-year cumulative recurrence rates were similar among the geographic groups (European 0.08, North American 0.07, and Asian 0.06, P = 0.61). Age was the only independent predictive factor for overall survival ( P < 0.001, HR = 1.089, 95% CI 1.056-1.123) in multivariable analysis. Types B3 and thymic carcinoma ( P = 0.003, HR = 3.932, 95% CI 1.615-9.576) were independent risk factors for increased recurrence. CONCLUSIONS: This study shows that the selection of the surgical approach and the extent of resection for Stage I and II thymic tumours differ by geographic region. However, these differences seem to have little impact on outcomes.