Thymoma natural history
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Amr Marawan, M.D. [2]
Overview
The main prognostic factors for recurrence and survival are the stage at diagnosis and whether a complete resection has been achieved. Other prognostic factors with less impact on prognosis are the histological subtype, tumour size at diagnosis, age, gender and presence or absence of myasthenia gravis.[1]
The natural history of thymoma certainly illustrates the tendency for local mediastinal recurrence and pleural ‘‘droplet’’ recurrence presumably caused by mediastinal pleural invasion after resection. Local recurrences have been noted in the surgical incision used to completely remove a thymoma.[1]
Natural history
Thymic malignancies are generally considered indolent tumours due to long recurrence intervals (median of 68 months). Overall, for patients diagnosed with a resectable thymic tumor, 16% of them will recur after radical resection, either locally with pleural or ganglionar recurrence or with distant metastases. The most common sites of distant recurrence are lung, liver, bone, kidney, brain and bone marrow.[1]
Complications
- Thymoma usually doesn't have complications other than the pressure effect that it might cause (sometimes presented as superior vena cava syndrome). The complications are mostly due to the associated autoimmune diseases (e.g. myasthenia gravis, pure red cell aplasia) or complications of surgical removal.
- Rarely thymomic malignancy of unknown etiology may arise and it accounts for 0.2–1.5% of all malignancies.
Complications of Radiotherapy
The most common complications with radiotherapy are: pulmonary fibrosis, pericarditis and myelitis. IMRT, a new technique of radiotherapy will hopefully have less toxicities.[1]
Complications of Surgery
The complications of the procedure is rare but they should be considered. Bleeding, infection, damage to other organs, nerve injuries(biateral phrenic nerve injury) and respiratory failure. Local recurrence is more common than distant especially in advanced stages of the disease. Recurrence was described 10-20 years after removal of the primary lesion, so long term follow up is very important.
Complications of Thymic Biopsy
In some rare cases pneumothorax or mediastinitis may occur.
Prognosis
Prognosis is much worse for stage III or IV thymomas as compared with stage I and II tumors. Invasive thymomas uncommonly can also metastasize, generally to pleura, bones, liver or brain in approximately 7% of cases.[2]
Patients with stage III and IV tumors may nonetheless survive for several years with appropriate oncological management.
The prognosis of thymoma depends on the following:
- The location of the tumor.
- The stage of the tumor.
- Whether the tumor can be removed completely by surgery.
- The patient's general health.
- Whether the cancer has just been diagnosed or has recurred.
The main prognostic factors for recurrence and survival are the stage at diagnosis and whether a complete resection has been achieved.
The prognostic significance of the histologic type is somewhat variable because of the subjectivity of the classification into lymphocyte predominant, epithelial predominant, and mixed. The mixed histologic type was associated with the worst prognosis. The presence of myasthenia gravis at diagnosis is of less prognostic significance today.[1]
Patients who have undergone thymectomy for thymoma should be warned of possible severe side effects after yellow fever vaccination. This is probably caused by inadequate T-cell response to live attenuated yellow fever vaccine. Deaths have been reported.
References
- ↑ 1.0 1.1 1.2 1.3 1.4 "A review of prognostic factors in thymic mali... [J Thorac Oncol. 2011] - PubMed - NCBI".
- ↑ Thomas CR, Wright CD, Loehrer PJ (1999). "Thymoma: state of the art". Journal of Clinical Oncology : Official Journal of the American Society of Clinical Oncology. 17 (7): 2280–9. PMID 10561285. Text "accessdate" ignored (help); Unknown parameter
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