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.

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.