Epidemiology of thymoma

Thymic tumours are a heterogeneous group of malignancies with a range of clinical presentations. The most common types are thymoma and thymic carcinoma, but overall it remains a rare cancer, and one without a clear aetiology. In this review of the epidemiology of the disease, the relationship between sex, age, and ethnicity is reviewed, along with limited evidence on the genetics of the condition. In terms of risk factors and potential causative factors, environmental exposures such as tobacco, radiation, alcohol, or diet, seem to be irrelevant, but there is some evidence linking the development of thymoma and thymic carcinoma with viral conditions, including Epstein Barr Virus. But data is not conclusive, and in the absence of large patient numbers, it is difficult to prove causation. There has been good research looking at the link between thymoma and other malignancies, either before or after the diagnosis. There does not appear to be a significant increased likelihood of thymoma following other malignancies. But, there is a suggestion, in several papers, that there is an increased risk of other malignancies following the diagnosis of thymoma, although the magnitude of this risk is disputed. There does appear to be an increased risk of non-Hodgkins Lymphoma after a diagnosis of thymoma, and this could be related to a disruption in T-cell function caused by either the disease process or the treatment directed at the thymoma. In summary though, it is a rare malignant process with a variety of presentations, often limited to the anterior mediastinum, and without an aggressive disease profile.