Results of surgical treatment of thymomas with special reference to the involved organs

Marx

et al. 2002

Cancer

349

276

BACKGROUNDIn 1999, a World Health Organization (WHO) committee published histologic criteria for distinct thymoma entities (labeled as Type A, AB, B1, B2, B3 thymomas) and for the heterogeneous group of thymic carcinomas, collectively called Type C thymomas. Whether WHO‐defined histologic thymoma subtypes are of independent prognostic relevance has yet to be proved.METHODSTwo hundred thymomas from the Shanghai Chest Hospital with a mean follow‐up time of 15 years (range, 1–246 months) were studied for the relevance of WHO histologic subtype and other factors (stage, therapy, and myasthenia gravis [MG]) for survival.RESULTSIn order of frequency, 68 patients (34.0%) had Type AB, 39 (19.5%) had Type B2, 36 (18.0%) had Type C, 27 (13.5%) had Type B3, 17 (8.5%) had Type B1, and 8 (4.0%) had Type A thymoma. Five cases (2.5%) were rare thymomas not mentioned in the WHO classification. Survival data showed significant differences among the histologic subtypes (log rank test: P < 0.001). Among patients with Type A and AB thymomas, none died of tumor; of the Type B1 thymoma patients, only one (5.9%) died at 22 months. Type B2, B3, and C thymomas had a significantly worse prognosis with 5‐year survival rates of 75.0%, 70.0%, and 48.0%, respectively. Ninety‐six patients (48.0%) were in Masaoka Stage I, 26 (13.0%) were in Stage II, 65 (32.5%) were in Stage III, and 13 (6.5%) were in Stage IV. Stage was highly significant in predicting survival (log rank, test P < 0.001). The association between histologic subtype and invasive behavior (stage) was statistically significant (P < 0.001). However, histology was an independent predictive factor of survival in Stage I and II thymomas: Type B2, B3, and C thymomas had a worse prognosis than Type A, AB, and B1 thymomas (log rank test: P < 0.003). Thirty patients (15.0%) presented with MG. MG was significantly more frequent in Type B2 and B3 than in Type A, AB, and B1 thymomas (P < 0.01). On multivariate analysis, MG had no adverse effect on survival (P = 0.17). Radiation or chemotherapy improved patients' survival at 5 and 10 years in Type B2, B3, and C thymomas (log rank test: P < 0.003).CONCLUSIONSTumor stage is the most important determinant of survival in thymoma patients, but the WHO histologic subtype is an independent prognostic factor in Stage I and II thymomas, among which WHO Type A, AB, and B1 thymomas form a low‐risk group. Patients with high‐risk thymomas might profit from novel adjuvant radiochemotherapy regimens. Cancer 2002;95:420–9. © 2002 American Cancer Society.DOI 10.1002/cncr.10665

Section: Discussioncontrasting

confidence: 99%

New WHO histologic classification predicts prognosis of thymic epithelial tumors

Marx

et al. 2002

Cancer

349

276

“…Our previous report 12 showed that the Masaoka staging system and involvement of the great vessels were independent prognostic factors. In univariate analysis, the current study also indicated that survival differed significantly with reference to involvement of the great vessels (Fig.…”

Section: Discussionmentioning

confidence: 96%

“…1,2 The prognostic factors for thymoma have been studied by many clinicians and researchers to establish a strategy for the treatment of patients with these tumors, including surgical resection, radiation therapy, and chemotherapy. Staging according to the classification system of Masaoka et al, 3 which is based on invasion to the surrounding organs, 3 completeness of resection, 4 -7 association with myasthenia gravis, 8 -10 tumor size, 11 and involvement of the great vessels, 12 reportedly can determine the postoperative survival of patients with thymoma. At the same time, the prognostic relevance of the histologic classification of thymoma has been discussed intensively [13][14][15][16][17] but remains to be determined.…”

mentioning

confidence: 99%

The World Health Organization histologic classification system reflects the oncologic behavior of thymoma

Okumura

Ohta

Tateyama

et al. 2002

Cancer

Self Cite

549

414

BACKGROUNDAlthough the histologic classification of thymic epithelial tumors has been confusing and controversial, an agreement on the universal classification system for thymic epithelial tumors was achieved by the World Health Organization (WHO) in 1999. The authors previously reported that the WHO histologic classification system reflects invasiveness and immunologic function of thymic epithelial tumors. In this subsequent study, they examined the prognostic significance of this classification system.METHODSClinical features as well as postoperative survival of patients with thymoma, but not thymic carcinoma, were examined with reference to WHO histologic classification based on an experience with 273 patients over a 44‐year period.RESULTSThere were 18 type A tumors, 77 type AB tumors, 55 type B1 tumors, 97 type B2 tumors, and 26 type B3 tumors. In patients with type A, AB, B1, B2, and B3 tumors, the respective proportions of invasive tumor were 11.1%, 41.6%, 47.3%, 69.1%, and 84.6%; the respective proportions of tumors with involvement of the great vessels were 0%, 3.9%, 7.3%, 17.5%, and 19.2%; and the respective 20‐year survival rates were 100%, 87%, 91%, 59%, and 36%. According to the Masaoka staging system, the 20‐year survival rates were 89%, 91%, 49%, 0%, and 0% in patients with Stage I, II, III, IVa, and IVb disease, respectively. By multivariate analysis, the Masaoka staging system and the WHO histologic classification system were significant independent prognostic factors, whereas age, gender, association with myasthenia gravis, completeness of resection, or involvement of the great vessels were not significant independent prognostic factors.CONCLUSIONSThis study showed that histologic appearance reflects the oncologic behavior of thymoma when the WHO classification system is adopted. The WHO classification system may be helpful in clinical practice for the assessment and treatment of patients with thymoma. Cancer 2002;94:624–32. © 2002 American Cancer Society.DOI 10.1002/cncr.10225

“…3) As stage III thymoma is highly heterogenous in terms of the involved organs, the classification should divide the subgroups according to prognosis. Okumura and associates (37) reported that involvement of the great vessels is an independent prognostic factor in patients with stage III thymoma. 4) The system is not well suited to staging thymic carcinomas (38,39).…”

Section: Clinical Stagementioning

confidence: 99%

Optimal therapy for thymoma

Kondo

2008

J. Med. Invest.

: Thymoma is the most common tumor of the anterior mediastinum. This tumor is associated with unique paraneoplastic syndromes (myasthenia gravis, pure red cell aplasia, hypogammaglobulinemia, and other autoimmune diseases). The rarity of this tumor has somewhat obscured the optimal treatment. Although the histologic classification of thymoma has remained a subject of controversy for many years, the WHO classification system, published in 1999, appeared to be an advance in our understanding of thymoma. The optimal treatment for thymoma depends on its clinical stage. Surgery remains the mainstay of treatment for thymic epithelial tumors. Thymomas also have a high response rate to chemotherapy or radiotherapy. Only surgical resection is performed for patients with stage I (non-invasive) thymoma. The value of postoperative radiotherapy in completely resected stage II or III tumors is questionable. Multimodality therapy involving surgery, chemotherapy and radiotherapy appears to increase the rate of complete resection and survival in advanced (stage III and IV) thymomas. J. Med. Invest. 55 : 17-28,