Malignant thymoma.

Abstract

Sixty-one patients underwent operations for malignant thymomas between 1961 and 1989. Twenty-three patients had associated myasthenia gravis (MG), an incidence of 37.7%. Upon being admitted to the hospital, the patients' most common symptoms included chest pain, MG, cough, and dyspnea. Only 7 of 61 (11.5%) patients had no symptom. Tumor staging of 58 patients with invasive thymomas was performed according to Masaoka classification. The patients were classified as follows: Stage II disease, 5; Stage III, 41; Stage IVa, 8; and Stage IVb, 4. In addition, thymic carcinoma was present in three patients. The series had a resection rate of 55.7%. The incidence of operative complications was 16.3%. Only one patient died of myocardial infarction; the incidence of operative mortality was 1.6%. The patients with MG had a higher rate of resection (69.6%) and a higher incidence of complete thymectomy (14 of 23 patients; 60.9%). Mixed lymphoepithelial tumors and epithelial cell predominant tumors were the most frequent histologic patterns (45.9% and 34.4%, respectively). Fifty-two patients had postoperative radiation therapy, and 10 patients had chemotherapy. The overall cumulative survival rates in the series were 59% and 34% at 5 and 10 years, respectively. The results demonstrated that the factors affecting the prognosis may include resectability, postoperative irradiation or chemotherapy, MG, and tumor staging. The influence of histologic variation on survival rates could not be clearly defined in the series. Surgical resection, particularly complete thymectomy, followed by irradiation is the primary option of therapeutic management for malignant thymoma.