Patients with thymomas have an increased risk of developing additional malignancies: lack of immunological surveillance?

Aims: To assess the risk, for patients with thymoma, of developing an additional malignancy (AM). Methods and results: We studied 68 patients with thymomas. Based on the World Health Organization classification, the tumours were categorised as A, AB or B (B1, B2, B3) thymomas. Control populations comprised 114 patients with colorectal cancer, 108 patients with lymphoma and 123 patients with thyroid carcinoma. Patients with thymomas showed a higher risk of developing an AM (22 of 68 patients versus 11 of 114, eight of 108, and eight of 123 patients, respectively; P=0.0002). The association between thymomas and AMs was related to the thymoma histotype, with B1, B2, B3 and AB tumours showing a higher risk of developing an AM than A thymomas (P=0.0474). Conclusions: Patients affected by thymomas showed a significantly higher risk of developing additional malignancies than those in the control groups, and cases that exhibited a predominantly cortical component were more likely to develop other neoplasms. This may be related to the functions of cortical thymic epithelial cells in providing for T lymphocyte maturation through interaction with major histocompatibility complexes