Perfection in the staging of thymic epithelial tumours: is it always obligatory? Free

The choice of the optimal treatment of thymic epithelial tumours (TETs) is an important and widely discussed issue, especially in patients with advanced tumours. In recent years, clinical stage III thymomas have usually been managed with neoadjuvant therapy and subsequent radical surgery [1–3]. The role of operative treatment with adjuvant chemotherapy in stage IV thymomas is more controversial, with a growing number of reports supporting such a strategy [2–4]. The most difficult situation is the treatment of thymic cancer, which has different pathological features compared to thymomas. Nevertheless, even in patients with thymic cancer, surgical treatment is recommended if feasible, in combination with chemoradiotherapy [2, 3].

The ability to distinguish between stage III and IV thymomas and thymic cancer is clinically important because it affects the management of these lesions. The publication of Qing Zhou and colleagues is intended to clarify this issue [1]. Their study is an attempt to provide objective criteria for the qualification of patients with TETs to obtain the most appropriate treatment modality. The authors analysed several characteristics of TETs and found that tumour edges, extracapsular fat, mediastinal vessels and pleura invasion and pericardial effusion are the factors most relevant to the classification and staging of TETs.

In my comments about this study, I would like to raise 2 points. First, unfortunately, this study does not add much new information to what has been already established about the radiological features of the TETs. Second, the relation between the diagnostics and the management of TETs is, in my opinion, even more important.

There is no doubt that some pieces of information gained from pretreatment diagnostic tests can influence the management of TETs. For example, if we know before commencing any treatment of thymoma that a tumour infiltrates the mediastinum, we would rather depart from primary surgical treatment and refer a patient for neoadjuvant therapy with the possibility of subsequent operative treatment. The other vitally important information concerns possible infiltration of the aorta or the pulmonary trunk because we cannot perform radical surgery in such a patient without the help of a cardiac surgeon and the use of extracorporeal circulation. In such cases, the need for an extremely precise diagnosis is apparent.

However, other factors analysed during the staging of TETs are less important and do not influence the management of these tumours in the crucial way that is needed when staging a lung cancer. One must remember that the indications for surgical treatment of TETs are much different from the indications for the surgical treatment of lung cancer. For example, a patient with a stage IVa thymoma is not automatically excluded from surgery as is a patient with stage IVa lung cancer (despite some rare attemps undertaken to treat patients with oligometastatic lung cancer). Therefore, in patients with clinical stage IVa thymomas, we have 2 possible treatment options—chemotherapy or surgery with removal of the thymus and all metastatic nodules [4, 5]. Detailed preoperative knowledge about metastatic nodules will not change our treatment strategy if we have decided to operate on such a patient.

There are other similarly controversial scenarios in which a detailed diagnosis is not absolutely obligatory for the therapeutic decision:

1. A patient had neoadjuvant therapy but the tumour probably still infiltrates the lung or the pericardium: In such cases, the infiltrations are not absolute contraindications to surgery if we are able to perform an R0 resection. Knowing whether there is infiltration is not vitally necessary.

2. If a patient has a marginally resectable tumour after neoadjuvant chemotherapy with suspicious but not proven metastases to the mediastinal nodes (despite mediastinal staging procedures), it is not absolutely necessary to determine if the mediastinal nodes are metastatic. Regardless of whether the nodes are metastatic or not, we decide to perform radical thymecomy with a mediastinal lymphadenectomy [6].

3. After neoadjuvant therapy, a TET is still marginally resectable, but we decide to perform debulking with subsequent radiotherapy if R0 resection is not possible [7].

In such clinical situations, the detailed knowledge provided by a chest CT is not critically necessary when deciding the optimal treatment modality.

The progress in the diagnosis of TETs should parallel the progress in the treatment of these tumours. There is no benefit for the patient if the diagnostic method is more advanced than the treatment.

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