A series of 90 thymic epithelial tumors were reviewed and classified by histopathologic characteristics into the three major categories (A, B, and C) recognized by the WHO schema. Each tumor type was correlated with patient characteristics and clinical data (age, sex, presence of myasthenia gravis, tumor size and invasiveness, and completeness of resection), and with outcome (survival, recurrence, and metastasis). All tumors were categorized by the WHO schema. Myasthenia gravis was present in 32 patients, mostly young and with type B thymic epithelial tumors. Tumors were invasive in 56% of cases, but resection was total in 67% of patients and only partial in the rest. Five factors were shown by univariate analysis to be associated with a favorable prognosis: presence of myasthenia gravis (p = 0.0389), younger age (p = 0.0022), completeness of resection (p = 0.0001), noninvasiveness (p = 0.0138), and tumor type A or B, as opposed to type C (p = 0.0001). Prognosis for types A and B was not significantly different, suggesting that the subtypes of types A and B thymic epithelial tumors should be regarded as a morphologic continuum rather than as distinct histologic variants.

We report on 17 years experience of the surgical treatment of thymoma in 65 patients, 11 with and 54 without myasthenia gravis. Patients were staged using the French "GETT" classification; 38 were in stage I (no invasive tumor), 6 in stage II, 13 in stage III and 8 in stage IV. In 45 patients, surgical excision was total while the remaining 20 underwent partial resection only. Postoperative radiotherapy was given in 12 cases, and 17 received a combination of radiotherapy and chemotherapy. One patient was lost to follow up, but no operative death occurred in the series. The mean survival for all patients was 70 +/- 7 months, and the 5- and 10-year survival was 91% +/- 4% and 69% +/- 8%, respectively. Follow-up for the 47 patients still alive and 4 patients deceased from unrelated causes ranged from 1.5 to 180 months (mean 142 +/- 10 months). Our data indicate that the prognosis of thymoma relates to radiological discovery (P less than 0.01), total surgical resection (P less than 0.01) and stage of tumor (P less than 0.01). It is not influenced by age, sex, tumor cell type or the presence or absence of myasthenia gravis.

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