Abstract
Simple SummaryThymic epithelial tumors were originally staged using the Masaoka–Koga staging system, even if recently the adoption of the tumor node metastases staging system was recommended. However, it remains controversial as to which staging system is the most effective in prognosis prediction for these patients. The aim of this study was to analyze the prognostic effectiveness of these staging systems and to verify a possible improvement. Background: The aim of this study was to evaluate the Masaoka–Koga and the tumor node metastases (TNM) staging system in thymic epithelial tumors (TET) considering possible improvements. Methods: We reviewed the data of 379 patients who underwent surgical resection for TET from 1 January 1985 to 1 January 2018, collecting and classifying the pathological report according to the Masaoka–Koga and the TMN system. The number of involved organs was also considered as a possible prognostic factor and integrated in the two staging systems to verify its impact. Results: Considering the Masaoka–Koga system, 5- and 10-year overall survival (5–10YOS) was 96.4% and 88.9% in stage I, 95% and 89.5% in stage II and 85.4% and 72.8% in stage III (p = 0.01), with overlapping in stage I and stage II curves. Considering the TNM system, 5–10YOS was 95.5% and 88.8% in T1, 84.8% and 70.7% in T2 and 88% and 76.3% in T3 (p = 0.02), with overlapping T2–T3 curves. Including the number of involved structures, in Masaoka–Koga stage III, patients with singular involved organs had a 100% and 76.6% vs. 87.7% 5–10YOS, which was 76.6% in patients with multiple organ infiltration. Considering the TNM, T3 patients with singular involved structures presented a 5–10YOS of 100% vs. 62.5% and 37.5% in patients with multiple organ involvement (p = 0.07). Conclusion: The two staging systems present limitations due to overlapping curves in early Masaoka–Koga stages and in advanced T stages for TNM. The addition of the number of involved organs seems to be a promising factor for the prognosis stratification in these patients.
Highlights
Thymic epithelial tumors (TET) are rare tumors occurring in the anterior mediastinum, and surgery is the treatment of choice ensuring excellent results in terms of disease control and long-term survival [1,2].Tumor staging started in the 80s, with a classification proposed by Dr Masaoka, which was revised with Dr Koga (Masaoka–Koga staging system) considering4 stages and classifying thymic epithelial tumors (TET) based on the infiltration of the neighboring structures or lymphatic/hematogenous spreading [3]
One of the most important challenges in TET staging is that the involvement can include one or more structures and the involvement of some structures may imply an involvement of another, e.g., lung infiltration is only possible after mediastinal pleural infiltration
Few studies compared the two staging systems [6,7,8,9], reporting controversial results in terms of prognosis, especially comparing advanced stages or considering overall survival, while a better performance was demonstrated considering stage I or disease-free survival (DFS). Another interesting point regards the role of the number of the involved structures, not considered in available staging systems and in validation studies, which may be beneficial for a better prognosis stratification
Summary
Thymic epithelial tumors (TET) are rare tumors occurring in the anterior mediastinum, and surgery is the treatment of choice ensuring excellent results in terms of disease control and long-term survival [1,2].Tumor staging started in the 80s, with a classification proposed by Dr Masaoka, which was revised with Dr Koga (Masaoka–Koga staging system) considering4 stages and classifying TET based on the infiltration of the neighboring structures or lymphatic/hematogenous spreading [3]. One of the most important challenges in TET staging is that the involvement can include one or more structures and the involvement of some structures may imply an involvement of another, e.g., lung infiltration is only possible after mediastinal pleural infiltration For these reasons, the TNM is based on the level of the infiltration concept, including the tumor in a certain “level” of involvement if either one or more than one structure of that level is involved, with or without the explicit involvement of structures included at a lower level [5]. The aim of this study was to evaluate the Masaoka–Koga and the tumor node metastases (TNM) staging system in thymic epithelial tumors (TET) considering possible improvements. Including the number of involved structures, in Masaoka–Koga stage III, patients with singular involved organs had a 100% and 76.6% vs 87.7% 5–10YOS, which was 76.6% in patients with multiple organ infiltration. Conclusion: The two staging systems present limitations due to overlapping curves in early
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