Staging

It is important to know the stage of a cancer or tumor, which also helps in selecting the treatment and it determines prognosis. Approximately 15-20% of patients with myasthenia gravis have a thymoma; so, in these patients it may be detected at an early stage.

As for other solid tumors, there is currently a TNM (tumor – node – metastasis) classification for thymic epithelial tumors comprising thymomas and thymic carcinomas. This was developed in collaboration with ITMIG and is the preferred classification at the present time. Finally, the patients are classified in 4 different stages (table 2). Those patients in an early stage have the best prognosis.

T component
T1 T1a encapsulated or unencapsulated, with or without extension into mediastinal fat
T1b extension into mediastinal pleura
T2 direct invasion of pericardium (partial or full-thickness)
T3 direct invasion of lung, brachiocephalic vein, superior vena cava, chest wall, phrenic nerve, and/or hilar (extrapericardial) vessels
T4 direct invasion of aorta, arch vessels, main pulmonary artery, myocardium, trachea or esophagus
N component
N0 no nodal involvement
N1 anterior (perithymic) nodes
N2 deep intrathoracic or cervical nodes
M component
M0 no metastatic pleural, pericardial, or distant sites
M1 M1a separate pleural or pericardial nodule(s)
M1b pulmonary intraparenchymal or distant organ metastasis
Stage grouping
I T1N0M0
II T2N0M0
IIIA T3N0M0
IIIB T4N0M0
IVA anyT N1 M0 – anyT N0,N1 M1a
IVB anyT N2 M0,M1a – anyT anyN M1b

Table 2. TNM (tumor – node – metastasis) classification of thymic epithelial tumors

[Detterbeck FC. J Thorac Oncol 2014; 9 suppl.2: S65-S72]

Stage Treatment

I – Complete surgical excision is the main treatment of thymic epithelial tumors on the condition that a complete resection can be obtained.

II – Complete surgical excision; in case of positive or borderline margins postoperative radiotherapy may be applied to decrease the incidence of local recurrence

III – Stage III tumors are borderline resectable; in case of involvement of tumor margins or in patients presenting a high risk for recurrence, postoperative radiotherapy is indicated to decrease the incidence of local recurrence; in some patients induction therapy may be considered; every patient has to be discussed on an individual basis in a multidisciplinary tumor board

IV – In stage IV tumors a combined modality approach is indicated which is tailored to the extent of the tumor, physiological fitness and performance status of the patient; treatment options include chemotherapy, targeted therapies, immunotherapy, radiotherapy and surgical debulking, or a combination thereof.