Prognostic factors and long-term results after thymoma resection: A series of 307 patients

Abstract

Three hundred seven cases of patients who underwent operation for thymoma (196 of whom had myasthenia gravis) were analyzed to assess the prognostic values of Masaoka clinical staging, completeness of resection, histologic classification, history of myasthenia gravis, and postoperative radiotherapy. According to the Masaoka staging system, 135 thymomas were stage I, 70 were stage II, 83 were stage III, and 19 were stage IV. According to the Verley and Hollmann histologic classification system, 67 thymomas were type 1, 77 were type 2, 139 were type 3, and 24 were type 4. Two hundred sixty patients underwent complete resection, 30 underwent incomplete resection, and 17 underwent biopsy. Postoperative radiotherapy was performed mainly in cases of invasive or metastatic thymoma. Mean follow-up was 8 years; eight patients were unavailable for follow-up. The overall 10- and 15-year survivals were 67% and 57%, respectively. In univariate analysis, three prognostic factors were established: completeness of resection, Masaoka clinical staging, and histologic classification. Furthermore, among patients with stage III thymomas, survival was significantly higher for patients with complete resection than for patients with incomplete resection (p < 0.001). Completeness of resection should therefore be taken into account in clinical-pathologic staging. We did not find any significant difference with respect to disease-free survival between patients who had postoperative radiotherapy and those who did not. In multivariate analysis, the sole significant prognostic factor was completeness of resection. On the basis of these findings, a new clinical-pathologic staging system is proposed.

WHO types A and AB thymomas: not always benign

“…27,51 However, the use of this factor in prognostication has been controversial as some studies have not found an association of survival with myasthenia gravis. 29,52,53 In this current series, types A and AB thymomas had a similar pattern of recurrence/metastasis and thus can be regarded as a single category. Indeed, Suster and Moran 54 have proposed a classification system that groups types A and AB along with types B1 and B2 under a single rubric of 'typical thymoma.'…”

“…Although some promote and anticipate a benign clinical course for these tumors, 6,[12][13][14][15][16] others (ourselves included) consider all thymomas as potentially malignant neoplasms. [1][2]10,[17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] Many prior studies have documented malignant behavior in types A and AB thymomas. In our retrospective study of 71 cases of types A and AB thymomas (37 cases with follow-up information available), 18 patients (nine each of types A and AB) developed recurrence and or metastases.…”

“…In majority of cases, relapses have been intrathoracic, although distant sites of progression include the lung, brain, liver, and thoracic spine. 22,29,36 Importantly, in most of these studies, complete excision of the tumor was reported. Interestingly, in the study by Rieker et al, 37 the 43 patients with type A tumors had a worse outcome when compared with patients with AB (n ¼ 20) and B1 (n ¼ 24) tumors.…”

“…26 It has been suggested that stage I tumors be further divided into stages Ia and Ib based on the absence or presence of peritumoral adhesions. 21,29 In some studies, recurrences were observed only among patients having intraoperative adhesions. 21,29 Patients with larger tumors appear to have worse prognoses.…”

“…21,29 In some studies, recurrences were observed only among patients having intraoperative adhesions. 21,29 Patients with larger tumors appear to have worse prognoses. 11,17,21,48 In this study, tumors 48 cm had 22 were not able to confirm the prognostic impact of the 8 cm cutoff; this may be due to the fact that there were very few large tumors in their series.…”