Thymoma: update for the new millennium.

Thymomas are relatively common tumors of the anterior superior mediastinum. They are usually relatively slowly growing tumors and their prognosis depends on the macroscopic and microscopic invasion of surrounding tissues. Surgery is the mainstay treatment of thymomas, and complete resection represents one of the most important prognostic factors in this disease. Other important prognostic indicators include the tumor stage and size and the presence of symptoms. Postoperative radiotherapy is indicated in tumors with invasion of surrounding tissues, even if resection was radical, since it improves local control and survival. Cytotoxic chemotherapy has been employed in several relatively small phase II studies and in advanced disease has been demonstrated to produce a 50%-80% objective response rate. Neoadjuvant cytotoxic chemotherapy and/or external beam radiotherapy has been used with some success in patients with tumors which are not readily resectable. Novel antiproliferative systemic agents, with both cytotoxic and cytostatic mechanisms of action, are being tested in ongoing prospective clinical trials.