Thymic Carcinoma – Symptoms, Diagnosis, and Treatment of Thymoma and Thymic Carcinoma

The thymus is part of the immune system and is integrated into the lymphatic system. Therefore, thymomas typically consist of abnormal epithelial cells, some T lymphocytes, and other immune system cells.

The most commonly used classification of thymic carcinoma is that of the World Health Organization (WHO). This classification divides the tumor into six classes (types A, AB, B1, B2, B3, and C) based on the cell of origin. Only thymic carcinoma types B3 and C are malignant in nature and have a poor prognosis.

Cancer cell @ vitanovski /AdobeStock

Clinical staging, which is also crucial for treatment, is based on the so-called Masaoka classification. Histological parameters and the pattern of spread of the thymic carcinoma are particularly important for this classification.

The latter also includes the formation of secondary tumors (metastases). In general, however, thymic carcinomas metastasize less frequently than other tumors. If metastases are present in a very advanced stage, they are more likely to be found in neighboring organs and tissues.

Thymomas grow slowly. Symptoms may not appear for a long time. As a result, thymic carcinoma is very often diagnosed incidentally. If tumor-related symptoms do occur, they are usually nonspecific. 

They usually include:

• Pain
• Cough
• Hoarseness or
• Breathing difficulties (dyspnea)

In addition, there are paraneoplastic syndromes, such as myasthenia gravis, which is found in up to 45% of patients.

Doctors often discover thymic carcinoma incidentally on an X-ray. The exact diagnosis of a thymoma is then made using computed tomography (CT).

A CT scan is used for diagnosis @ Gorodenkoff /AdobeStock

Clinical staging, which is also crucial for treatment, is based on the so-called Masaoka classification. Histological parameters and the pattern of spread of the thymic carcinoma are particularly important for this.

The latter also includes the formation of secondary tumors (metastases). In general, however, thymic carcinomas metastasize less frequently than other tumors. If metastases are present in a very advanced stage, they are more likely to be found in neighboring organs and tissues.

Thymomas grow slowly. Symptoms may not appear for a long time. As a result, thymic carcinoma is very often diagnosed incidentally. If tumor-related symptoms do occur, they are usually nonspecific. 

They usually include:

• Pain
• Cough
• Hoarseness or
• Breathing difficulties (dyspnea)

In addition, there are paraneoplastic syndromes, such as myasthenia gravis, which is found in up to 45% of patients.

Doctors often discover thymic carcinoma incidentally on an X-ray. The exact diagnosis of a thymoma is then confirmed with a computed tomography (CT) scan.

If surgery is not possible, doctors resort to a combination of radiation therapy and chemotherapy to treat thymic carcinoma. 

Reasons why thymic carcinoma may be inoperable include:

• poor general health of the patient
• serious comorbidities
• The tumor is too large 
• The tumor has grown invasively

The prognosis for patients with thymic carcinoma (thymoma) is closely related to the Masaoka stage at diagnosis, e.g.:

• In Stage I, the 5-year survival rate is 100% and the recurrence rate is < 0.9%.
• In Stage III, the 5-year survival rate is still 89%, but the recurrence rate rises to 28.4%.
• Finally, in Stage IVa, the 5-year survival rate is 71%, and the recurrence rate is 34.3%.

Early diagnosis and treatment at a low stage of the disease therefore offer the best chances of a cure.

Doctors who treat thymic carcinoma are mostly specialists in general and thoracic surgery as well as oncologists.

Due to their diversity, thymomas and thymic carcinomas fall within the broad field of interdisciplinary oncology in terms of treatment.

They therefore require collaboration between surgeons and other medical specialists. This also applies to the follow-up care of patients.

What is thymic carcinoma?
Thymic carcinoma is a malignant tumor of the thymus gland in the chest cavity. The disease is classified as a rare epithelial thymus tumor and differs from a thymoma in that it is significantly more aggressive. Thymic carcinomas can spread to surrounding tissues or distant parts of the body.

What symptoms does thymic carcinoma cause?
Typical symptoms include cough, chest pain, shortness of breath, and difficulty swallowing. Some tumors remain asymptomatic for a long time and are only discovered by chance. In addition, paraneoplastic or autoimmune diseases such as myasthenia gravis may occur.

How is the diagnosis made?
Computed tomography (CT), X-rays, and tissue examination are used for diagnosis. Histological findings, as well as the extent of tumor spread within the mediastinum or pericardium, are crucial. The timing of the diagnosis often influences the prognosis and treatment options.

How is thymic carcinoma treated?
Treatment usually consists of surgical removal followed by standard therapy with chemotherapy or radiation therapy. In cases of advanced disease, participation in a clinical trial may also be advisable. Removal of the tumor often improves the prognosis.

What is the prognosis for thymic carcinoma?
The prognosis depends on the stage, metastasis, and aggressiveness of the thymic carcinoma. Compared to thymoma, thymic carcinomas are often considered more difficult to treat and are associated with a poorer prognosis. People with thymic carcinoma therefore usually require lifelong follow-up care.