Thymoma

Objective: We evaluated the prognostic factors for thymoma that remain controversial.Methods: We studied 72 consecutive patients treated for thymoma during the period between 1966 and 1997. Recurrence-free interval rates and overall survival rates calculated by the Kaplan-Meier method were compared using logrank test by the Masaoka stage, extent of surgical resection, histology, or associated disease(s). Multivariate analysis was performed using Cox's proportional hazards model.Results: Thirty-two thymomas were at Masaoka stage I, 9 at stage II, 15 at stage III, and 16 were at stage IV. There were 56 complete resections, 7 incomplete resections (2 at stage III and 5 at stage IV), and 9 biopsies (1 at stage III and 8 at stage IV). Forty-one thymomas were cortical, 16 medullary, and 15 were mixed form. Association of myasthenia gravis was found in 20 patients, and pure red cell aplasia in 7. After an average follow-up period of 103 months, the recurrence-free 5-, 10-, 15-year interval rate was 89%, 80%, 80%, respectively, and overall 5-, 10-, 15-year survival rate was 86%, 71%, 59%, respectively. Factors influencing the recurrence-free interval and overall survival included the Masaoka stage, extent of surgical resection, and association with pure red cell aplasia. Multivariate analysis revealed stage IV tumor and association with pure red cell aplasia as risk factors for recurrence. Pure red cell aplasia indicated poor prognosis for overall survival.Conclusions: Masaoka stage, extent of surgical resection, and association with pure red cell aplasia were prognostic factors for thymoma. Multidisciplinary treatment for stage IV tumors and better control of pure red cell aplasia, if associated, should be investigated.     

Does adjuvant radiation therapy improve disease-free survival in completely resected Masaoka stage II thymoma?

OBJECTIVE: To determine whether or not patients with completely resected Masaoka stage II thymoma benefit from postoperative radiotherapy (RT). METHODS: We retrospectively review the case records and compared the long-term outcomes of patients affected by Masaoka stage II thymoma treated by resection alone with same stage thymoma patients submitted to resection and RT. Surgical specimens were reviewed to confirm pathological stage, negative resection margins and histological subtype. RESULTS: Between 1988 and 2000, we performed 197 resections for thymoma; 58 patients resulted to be affected by completely resected tumours with microscopic transcapsular invasion (stage IIA, n=25) or macroscopic invasion into the surrounding fatty tissue with or without adhesion to the mediastinal pleura (stage IIB, n=33). Thirty-two patients underwent only complete surgical resection (14 stage IIA and 18 stage IIB); 26 patients underwent complete resection and subsequent mediastinal RT (11 stage IIA and 15 stage IIB). RT dosages were 45-54grays (Gy), in 25-30 fractions. Histological subtypes were similarly represented in both groups. Median follow-up was 91 months (range 9-170). Five intrathoracic recurrences occurred: three radiated patients (2 stage IIB - 1 AB and 1 B2 thymoma; 1 stage IIA B1 thymoma) and two not-radiated patients (1 stage IIA AB thymoma and 1 stage IIB B1 thymoma). Disease-free survival rate at 5- and 10-year were 94% and 87%, respectively. Log-rank test showed no difference in Kaplan-Meier survival curves (p=0.432) between radiated and not-radiated patients. CONCLUSIONS: These data support the concept that radical surgical resection alone should be considered a sufficient treatment for stage II thymoma.     

Long-term survival and prognostic factors in thymic epithelial tumours.

OBJECTIVE: The aim of this study is to analyze long-term survival and the prognostic significance of some factors after surgical resection of thymic epithelial tumours. METHODS: We performed a retrospective analysis of clinical and histopathological data on 132 patients operated on for thymic tumours, from 1970 and 2001. Histologic diagnosis based on the new WHO classification system was made by a single pathologist. A univariate and multivariate analysis of prognostic factors predicting survival was carried out. RESULTS: There were: 108 complete resections (81.8%), 12 partial resections (9.1%) and 12 biopsies (9.1%). Overall 5, 10 and 15-year survival rate was 72, 61 and 52.5%, respectively. The Masaoka staging system showed 44 stage I, 18 stage II, 52 stage III and 18 stage IV. Histologic results were: 14 subtype A, 31 AB, 20 B1, 28 B2, 29 B3 and 10 C; the respective proportions of invasive tumour (stage II-IV) was 28.6, 58.1, 50, 75, 86.2 and 100%. There were 16 tumour recurrences (14.8%) of 108 radically resected thymomas, 10 were treated with radical re-resection. In univariate analysis, four prognostic factors were statistically significant: radical resection, Masaoka clinical staging, WHO histologic subtype and resectable tumour recurrence. In multivariate analysis, the independent factors predicting long-term survival were WHO histology and Masaoka stage. CONCLUSIONS: The WHO histologic classification seems to be the most significant prognostic factor reflecting the invasiveness of the thymic tumour. Completeness of resection and Masaoka stage I and II assure a better survival. Unresectable recurrence of thymic tumour predicted a worse prognosis.     

Clinical usefulness of the WHO histological classification of thymoma.

PURPOSE: Rosai et al. published the World Health Organization (WHO) classification of thymic epithelial tumors in 1999, and its clinical usefulness seems to be established. It is our purpose to find the clinically relevant diagnostic points in the WHO Histological Classification of Thymoma. METHODS: Thymomas surgically removed from 100 consecutive patients at Juntendo University Hospital between October 1983 and February 2002 were classified according to the WHO histological classification. We assessed overall survival and recurrence-free rate calculated for each tumor type in the WHO classification compared with those of tumors classified by the Masaoka system. RESULTS: The thymic epithelial tumors in this series comprised 10 type A, 15 type AB, 18 type B1, 21 type B2, 33 type B3, and 3 type C tumors according to the WHO classification. Based on the Masaoka system, the disease was stage I in 53 patients, stage II in 30, stage III in 15, and stage IV in 2. The 15-year recurrence-free rate was 100% for type A, AB and B1, while the rates for types B2 and B3 were 66.7% and 54.5%, respectively. The 10-year recurrence-free rate was 66.7% for type C. The 15-year recurrence-free rate of the 64 patients with type A, AB, B1, and B2 thymomas was significantly higher from that of the 33 patients with type B3 thymoma (p=0.0026). CONCLUSION: When using the WHO classification, it is critical to distinguish type B3 thymoma from other tumor types.     

侵袭性胸腺瘤手术治疗预后因素的随访

目的 观察侵袭性胸腺瘤的手术治疗效果,并分析影响患者预后的相关因素.方法 回顾性分析2000年1月至2009年12月接受手术治疗的59例侵袭性胸腺瘤患者的临床及随访资料.患者为连续病例,男性34例,女性25例;年龄18～72岁,平均49岁.根治性手术44例,姑息切除或活检15例.Masaoka分期:Ⅱ期18例,Ⅲ期30例,Ⅳ期11例;Ⅱ期患者术后未接受辅助放疗或化疗,Ⅲ、Ⅳ期患者术后接受辅助放疗和(或)化疗26例,未接受辅助放疗或化疗15例.分析手术方式、Masaoka分期、辅助放疗和(或)化疗与患者预后的关系.结果 本组59例患者随访时间1～111个月,平均54个月;失访3例,失访率6.1%.全组局部复发或全身转移19例,死亡14例,3年、5年生存率分别为86.8%、70.8%.单因素分析显示接受完全性切除手术、Masaoka分期较早及术后接受辅助放疗和(或)化疗的患者有较高的生存率(P＜0.05).多因素分析显示是否完全性切除、术后接受辅助放疗和(或)化疗是影响患者预后的独立因素(P＜0.05).结论 Masaoka分期与侵袭性胸腺瘤患者预后相关;完全性切除手术及术后辅助放化疗可显著提高患者生存率;部分复发患者再次手术后亦可获得长期生存.     

Analysis of surgical treatment of Masaoka stage III-IV thymic epithelial tumors

Objective

The purpose of this study is to elucidate the outcomes after surgical resection of Masaoka stage III-IV thymic epithelial tumors.

Methods

We retrospectively reviewed patients with Masaoka stage III-IV thymic epithelial tumor who underwent surgical resection from January 1995 to January 2017. The clinicopathological features, surgical procedures, and postoperative outcomes were investigated.

Results

Thirteen patients with thymoma and 18 patients with thymic carcinoma were assessed. The postoperative Masaoka stages were III/IVa/IVb?=?8/4/1 in thymoma and III/IVa/IVb?=?11/2/5 in thymic carcinoma. In patients with thymoma, the World Health Organization pathological subtypes were A/B1/B2/B3?=?2/1/4/6. We performed combined resection and reconstruction for brachiocephalic vein or superior vena cava in 3 patients with thymoma and 7 patients with thymic carcinoma. In all patients, the patency rate of the grafts was very low for the left brachiocephalic vein and well maintained for the right brachiocephalic vein. Macroscopically and pathologically complete resection was achieved in 11 and 6 patients with thymoma, respectively, and in 15 and 9 patients with thymic carcinoma, respectively. The 10-year survival rates were 85.7% in thymoma and 70.3% in thymic carcinoma. Postoperative recurrences were observed in 2 and 9 patients with thymoma and thymic carcinoma, respectively. Recurrences were observed within 5 and 10 years after surgery in 2 patients with thymoma and within 2 years in all patients with thymic carcinoma.

Conclusions

Patients with Masaoka stage III-IV thymic epithelial tumor showed relatively favorable long-term survival after surgical treatment. Therefore, aggressive surgical resection for complete resection may be a treatment option for these conditions.

     

Therapy for thymic epithelial tumors: a clinical study of 1,320 patients from Japan

BACKGROUND: Surgery remains the mainstay of treatment for thymic epithelial tumors, and radiation and chemotherapy also have been applied widely as adjuvant and palliative procedures. METHODS: We compiled records of 1,320 patients with thymic epithelial tumors who were treated from 1990 to 1994 in 115 institutes certified as special institutes for general thoracic surgery by The Japanese Association for Chest Surgery. RESULTS: Patients with stage I thymoma were treated with only surgery, and patients with stage II and III thymoma and thymic carcinoid underwent surgery and additional radiotherapy. Patients with stage IV thymoma and thymic carcinoma were treated with radiation or chemotherapy. The Masaoka clinical stage is an excellent predictor of the prognosis of thymoma and thymic carcinoma, but not thymic carcinoid. In stage III and IV thymoma, the 5-year survival rates of total resection, subtotal resection, and inoperable groups were 93%, 64%, and 36%, respectively. On the other hand, in thymic carcinoma, the 5-year survival rates of total resection, subtotal resection, and inoperable groups were 67%, 30%, and 24%, respectively. Prophylactic mediastinal radiotherapy could not prevent local recurrences effectively in patients with totally resected stage II and III thymoma. Adjuvant therapy including radiation or chemotherapy did not improve the prognosis in patients with totally resected III and VI thymoma and thymic carcinoma. CONCLUSIONS: Total resection is the most important factor in the treatment of thymic epithelial tumors. There is value in debulking surgery in invasive thymoma, but not in thymic carcinoma. We doubt that adjuvant therapy is valuable for patients with totally resected invasive thymoma and thymic carcinoma.     

Thymoma: results of 241 operated cases

Clinical and histopathological aspects of 241 thymomas were reviewed. One hundred sixty of the patients with thymoma had myasthenia gravis and 15 had other autoimmune diseases; 55% of the thymomas were encapsulated and 45% invasive. Operation was radical resection in 87.5% of the patients, subtotal resection with residual tumor in 8.7%, and simple biopsy in 3.7%. A tumor relapse was observed in 24 patients (10%): 2 (1.5%) of 133 with encapsulated thymomas and 22 (20.4%) of 108 with invasive thymomas; among these patients, a relapse was found in 20.6% of the patients who received radiotherapy postoperatively and in 24.6% who did not. Adverse prognostic factors were clinical stage IVa (multiple pleural nodes), not feasible resection (for technical reasons), inoperable tumor relapse, and association with one of the following autoimmune diseases: pure red cell aplasia, hypogammaglobulinemia, and lupus erythematosus. Conversely, myasthenia gravis is now a curable disease; it contributes to early discovery of associated thymoma, thus allowing a better survival for patients with thymoma who have myasthenia gravis compared with patients with thymoma but without myasthenia gravis (p less than 0.05). Postoperative radiotherapy does not seem necessary after removal of encapsulated thymomas, but it is advisable in case of invasive thymomas, regardless of the extent of the resection.     

Myasthenia gravis affects overall survival in patients with thymoma: an analysis of multicentre database using propensity score matching

Open in a separate window OBJECTIVESAbout one-third of patients with thymoma have myasthenia gravis (MG). It remains controversial whether MG affects the prognosis of patients with thymoma. The aim of this study was to evaluate the effect of MG on the prognosis of patients with thymoma in a multicentre database.METHODSPatients with thymoma who underwent thymectomy were identified from 2 prospectively collected databases in 2 medical centres from 2010 to 2018. Kaplan–Meier curves and the log-rank test were used to assess overall survival and recurrence-free survival, and a Cox proportional hazards model was used to determine significant contributors to survival. Propensity score matching was performed to eliminate selection bias.RESULTSA total of 514 patients with thymoma were included in this study, of whom 320 patients were MG-free and 194 had MG. Patients with MG were younger (median age 50 vs 54 years, P = 0.001) and had smaller tumours (4.4 ± 2.0 vs 4.9 ± 2.3 cm, P = 0.020). Pathological analysis showed that type B tumours especially B2−B3 (B2 + B3 + mix B tumours, 55.2%) are more common in patients with MG, while type AB (37.2%) was the most common in patients without MG. A larger proportion of Masaoka III–IV stage tumour (25.7% vs 11.0%, P < 0.001) was seen in patients with thymoma and MG. Multivariable Cox regression analysis demonstrated that MG (hazard ratio [HR] = 3.729, 95% confidence interval [CI]: 1.398–9.947, P = 0.009), incomplete resection (HR = 5.441, 95% CI: 1.500–19.731, P = 0.010) and Masaoka stage III + IV (HR = 3.390, 95% CI: 1.196–9.612, P = 0.022) were negative prognostic factors of overall survival. Meanwhile, MG (HR =3.489, 95% CI: 1.403–8.680, P = 0.007) and Masaoka stage III + IV (HR = 6.582, 95% CI: 2.575–16.828, P < 0.001) were negative prognostic factors of recurrence-free survival. Propensity-matched analysis compared 148 patient pairs. K-M survival analysis demonstrated that MG was associated with worse overall survival and recurrence-free survival in propensity score-matched patients (log-rank, P = 0.034 and 0.017, respectively).CONCLUSIONSThymoma patients with MG have smaller tumours and a higher percentage of late-stage tumours, which are mainly of WHO B types, especially B2−B3 types. In addition, MG is significantly associated with worse overall survival and recurrence-free survival in thymoma.     

Thymoma: results with complete resection and adjuvant postoperative irradiation in 141 consecutive patients

A series of 141 patients with thymoma was studied with regard to the way in which complete resection followed by postoperative radiation therapy influenced prognosis according to the stage and histologic type of thymoma. Postoperative radiation therapy (30 Gy in 3 weeks to 50 Gy in 6 weeks) was performed in 73.1% of the patients. Thirty-five of 48 patients with thymoma invading the surrounding tissues (stage III) underwent complete resection, with survival rates of 100% at 5 years and 94.7% at 10 and 15 years. The prognosis in these patients was comparable with those in 45 patients with no invasion (stage I) and in 33 patients with capsular invasion (stage III), all of whom underwent complete resection. Complete resection was done in 18 of 26 patients with epithelial cell thymoma, and there were no deaths by tumor until 15 years after the operation. There were no statistically significant differences in the survival rates of patients undergoing complete resection according to cell type (33 of 36 patients with lymphocyte predominant type and 61 of 77 patients with mixed cell type). The survival rate in six patients with epithelial cell type who underwent subtotal resection was not significantly different from that of 12 patients who underwent biopsy alone. Our findings indicate that complete resection of thymoma followed by postoperative radiation therapy results in a "benign" postoperative course, regardless of the stage and histologic type. Therefore, an aggressive surgical approach, such as resection of the superior vena caval system followed by reconstruction with a ringed polytetrafluoroethylene graft and/or complete pleuropneumonectomy, is justified for advanced thymoma, although the long-term results of such extended operations are still unclear.     

胸腺瘤患者预后因素分析

目的 探讨影响胸腺瘤患者术后远期生存率的相关因素。方法 回顾性分析我科1973—2000年间手术治疗的69例胸腺瘤，应用Kaplan—Meier法和Cox比例风险模型对可能影响胸腺瘤术后远期生存率的因素进行单因素和多因素分析。结果 全组患者5年、10年、15年生存率分别为83．3％、67．4％、41．9％。单因素分析显示年龄、Masaoka分期、WHO组织学分类、肿瘤切除范围、Rosai／Levine分类对胸腺瘤患者术后长期生存率有显著影响(P＜0．01)，但经多因素分析表明仅Masaoka分期(P＜0．01)、肿瘤切除范围(P＜0．05)、年龄(P＜0．05)是独立的预后因素。结论 对胸腺瘤应积极进行手术治疗，即使姑息性切除亦有助于提高远期生存。     

Multimodality Treatment of Thymoma: A Prospective Study

Background. Thymomas are a heterogeneous group of tumors. Treatment of invasive lesions is not well standardized. The aim of this study is to propose a clinicopathologically based protocol for multimodality therapy.

Methods. Between 1965 and 1988, we operated on 83 patients with thymoma who did not receive standardized adjuvant therapy. In 1989, on the basis of the retrospective analysis of the data, we started a multimodality therapy protocol and used it for 65 patients. Twelve patients had medullary thymoma (11 stage I and 1 stage II), 13 had mixed type (6 stage I and 7 stage II), and 40 had cortical thymoma (4 stage I, 11 stage II, 12 stage III, and 13 stage IV). We considered three groups. Group I (n = 18 patients), benign thymoma, included stage I and II medullary and stage I mixed thymomas; radical resection with no adjuvant therapy was performed. Group II (n = 22), invasive thymoma, included stage I and II cortical and stage II mixed thymomas; postoperative chemotherapy plus radiotherapy was always administered. Group III (n = 25), malignant thymoma, comprised stage III and IV cortical thymomas and stage III mixed thymomas; resectable stage III lesions were removed, and highly invasive stage III and stage IV lesions underwent biopsy, neoadjuvant chemotherapy, and surgical resection; postoperative chemotherapy and radiotherapy was administered to all patients.

Results. The 8-year survival rate for patients in stages I, II, III, and IV was 95%, 100%, 92%, and 68%, respectively. Patients with medullary thymoma had a 92% 8-year survival rate; those with mixed type, 100%; and those with cortical thymoma, 85%. Group I had an 8-year survival rate of 94%; group II, 100%; and group III, 76%. Survival was compared with that of patients operated on before 1989: differences were not significant for group I; survival improved in group II (100% versus 81%; p = not significant); and group III showed significant improvement (76% versus 43%; p < 0.049).

Conclusions. Multimodality treatment with neoadjuvant chemotherapy and adjuvant chemotherapy plus radiotherapy may improve the results of radical resection and the survival of patients with invasive and malignant thymoma.     

Invasive thymoma associated with pure red cell aplasia and liver metastasis: a case report]

A case of invasive thymoma associated with pure red cell aplasia and liver metastasis was reported. A 57-year-old male was admitted to our hospital because of hepatic abnormal shadow on computed tomography. Malignant tumor was suspected by imaging procedures. Left lateral segmental resection of liver was performed and histo-pathological examination proved the tumor to be liver metastasis of thymoma. He was received 50 Gy irradiation after incomplete resection of thymoma. In the course of time he contracted pure red cell aplasia. But he is well controlled medically and alive 7 years after the surgery.     

重症肌无力合并胸腺瘤的外科治疗(附31例报告)

报告１９８０年至１９９６年１０月手术治疗３１例重症肌无力合并胸腺瘤的结果。３１例占同期手术治疗１２０例重症肌无力之２５．８％。按Ｍａｓａｏｋａ分期属Ｉ期７例，Ｉ期８例，ＩＩ期１５例，ＩＶ期１例，术后１５例发生危象，均采用气管切开及辅助呼吸，１例死于危象。随访半年至８年，平均３７个月，５年内死亡６例，其中ＩＩ期４例，Ｉ期２例。结论：重症肌无力合并胸腺瘤术后危象的发生率远较未合并胸腺瘤者高，及时气管切开行辅助呼吸是处理的关键；胸腺瘤的Ｍａｓａｏｋａ病理分期与预后明显相关，肌无力的严重程度对预后亦有重要影响     

Thymoma: a clinicopathologic study based on the new World Health Organization classification

OBJECTIVE: This study explored the relationship between the histologic subtype of thymoma according to the new World Health Organization histologic classification and the clinical findings, as well as the prognostic significance of the classification. METHODS: A total of 130 patients with thymoma, who underwent resection at the National Cancer Center Hospital, Tokyo, from 1962 to 2000, were studied retrospectively. The histologic subtype of thymoma was determined according to the new World Health Organization histologic classification. The stage was also determined according to a modified Masaoka's classification as stage I, II, III, IVa, or IVb. To determine the factors that may affect the prognosis of thymoma, a multivariate analysis with Cox's proportional hazards regression model was performed. RESULTS: The distribution of histologic subtype was type A (n = 18), type AB (n = 56), type B1 (n = 15), type B2 (n = 29), and type B3 (n = 12). A close correlation was seen between the histologic subtype and stage (P =.000). The overall survivals at 5 and 10 years were 92% and 91%, respectively. The 5- and 10-year survivals according to stage were 100% and 100% (stage I, n = 40; stage II, n = 54), 81% and 76% (stage III, n = 25), and 47% and 47% (stage IV, n = 11), respectively. The difference in survival between stage III and stage IV was significant (P =.000). Patients with type A or AB thymoma demonstrated a 100% survival at both 5 and 10 years. Recurrences were seen in 12 patients with complete resection. According to a multivariate analysis, tumor size (P =.001), completeness of resection (P =.002), histologic subtype (P =.011), and stage (P =.00) were significant prognostic factors. CONCLUSION: The World Health Organization histologic classification significantly correlated with the clinical stage. Tumor size, completeness of resection, histologic subtype, and stage predicted the prognosis of thymoma.     

Results from surgical treatment for thymoma. 43 years of experience.

OBJECTIVE: The biological behavior of thymoma and its prognosis after surgical intervention remain still controversial. The efficacy of surgical treatment for thymoma was investigated by examining long-term follow-up data. SUBJECTS AND METHODS: Follow-up data for patients undergoing surgical resection of histopathologically-confirmed thymoma between 1954 and 1997 were obtained and were retrospectively analyzed. Clinical staging was based on Masaoka's staging system, and histological classification on Rosai's proposed criteria. RESULTS: Data for 140 patients were collected. Sixty-four patients had stage I, 32 had stage II, 28 had stage III, and 16 had stage IV thymoma. There were significant differences in survival between patients with stage I and stage III, stage I and stage IV and stage II and stage III disease, but not between those with stage I thymoma and stage II thymoma. No significant difference in survival was observed between the 56 patients with myasthenia gravis (MG) and the 84 without MG. The 38 patients classified as having a predominantly-epithelial thymoma had a poorer prognosis than the 41 with a predominantly-lymphocytic thymoma. Until 1975, there were four patients with stage I thymomas who later showed recurrence, compared with 21 among those with stage II, III and IV diseases. Since 1976, extended thymectomy with thymomectomy under median sternotomy has been adopted as the standard operation for a thymoma, and there has been no recurrence in stage I patients. CONCLUSIONS: Patients with stage III or IV invasive thymoma have a poorer prognosis and a higher recurrence rate than those with encapsulated thymoma, and patients with a predominantly-epithelial thymoma have a poorer prognosis than those with a predominantly-lymphocytic thymoma. Extended thymectomy with thymomectomy under median sternotomy can be considered as adequate treatment for a stage I thymoma. Myasthenia gravis does not appear to affect the prognosis of patients with a thymoma.     

Long-term outcome after multimodality treatment for stage III thymic tumors

BACKGROUND: Surgery remains the cornerstone of therapy for thymic tumors, but the optimal treatment for advanced, infiltrative lesions is still controversial. The introduction of multimodality protocols has substantially modified survival and recurrence rate. We reviewed our 13-year prospective experience with multimodality treatment of stage III thymoma and thymic carcinoma. METHODS: Since 1989 we have prospectively used a multimodality approach in 45 stage III thymic tumors. Sixteen patients (35%) had myasthenia gravis. Twenty-three patients (51%) had pure or predominantly cortical thymoma (group 1), 11 (24.5%) had well-differentiated thymic carcinoma (group 2), and 11 (24.5%) had thymic carcinoma (group 3). Tumors that were not considered radically resectable at preoperative workup underwent biopsy and induction chemotherapy (15 patients, 33%) followed by surgical resection; all patients were referred for adjuvant chemoradiotherapy. RESULTS: No operative mortality was recorded; 1 treatment-related death during adjuvant chemotherapy was observed in group 1. Complete resection was feasible in 91% of patients in groups 1 and 2 and 82% in group 3. The overall 10-year survival was 78%. Ten-year survival for groups 1 and 2 was 90% and 85%, respectively; 8-year survival for group 3 was 56%. During follow-up, tumor recurrence was noted in 3 patients (13%) from group 1, 3 (27%) from group 2, and 3 (27%) from group 3. CONCLUSIONS: Multimodality treatment with induction chemotherapy (when required) and adjuvant chemoradiotherapy offers encouraging results for stage III thymic tumors; the outcome is more favorable for cortical thymoma and well-differentiated thymic carcinoma.     

Results of Re-resection for Recurrent Thymomas

Background. The treatment of recurrent thymomas remains controversial.

Patients. The place for re-resection was retrospectively studied in 28 consecutive patients operated on during the last 40 years. The initial Masaoka staging of the thymoma was stage I, 4; stage II, 8; stage III, 11; and stage IVa, 3. Postoperatively, 14 have had radiation therapy, 1 chemotherapy, and 13 no adjuvant treatment. Seven patients had development of recurrences, 15 had pleuropulmonary metastases, 5 had both, and 1 had thoracotomy scar recurrence. Nineteen patients had a complete resection and 9 an incomplete one.

Results. Most local recurrences appeared after resection of stage I or II thymomas. On the other hand, in patients with stage III or IV thymomas pleural or pulmonary metastases mainly developed. No local recurrence occurred in patients who initially received postoperative radiation therapy. Five-year and 10-year survival rates were 51% and 43%, respectively, for the overall population. Among the 19 patients with complete resection, only 3 patients had a subsequent recurrence; 1 of them could be reoperated on and is still alive and free of disease.

Conclusions. Thymoma recurrences often appear as a locoregional rather than a hematogenous spread. Re-resection can be recommended in selected patients.     

Prognostic relevance of Masaoka and Müller-Hermelink classification in patients with thymic tumors

BACKGROUND: To compare the prognostic relevance of Masaoka and Müller-Hermelink classifications. METHODS: We treated 71 patients with thymic tumors at our institution between 1980 and 1997. Complete follow-up was achieved in 69 patients (97%) with a mean follow up-time of 8.3 years (range, 9 months to 17 years). RESULTS: Masaoka stage I was found in 31 patients (44.9%), stage II in 17 (24.6%), stage III in 19 (27.6%), and stage IV in 2 (2.9%). The 10-year overall survival rate was 83.5% for stage I, 100% for stage IIa, 58% for stage IIb, 44% for stage III, and 0% for stage IV. The disease-free survival rates were 100%, 70%, 40%, 38%, and 0%, respectively. Histologic classification according to Müller-Hermelink found medullary tumors in 7 patients (10.1%), mixed in 18 (26.1%), organoid in 14 (20.3%), cortical in 11 (15.9%), well-differentiated thymic carcinoma in 14 (20.3%), and endocrine carcinoma in 5 (7.3%), with 10-year overall survival rates of 100%, 75%, 92%, 87.5%, 30%, and 0%, respectively, and 10-year disease-free survival rates of 100%, 100%, 77%, 75%, 37%, and 0%, respectively. Medullary, mixed, and well-differentiated organoid tumors were correlated with stage I and II, and well-differentiated thymic carcinoma and endocrine carcinoma with stage III and IV (p < 0.001). Multivariate analysis showed age, gender, myasthenia gravis, and postoperative adjuvant therapy not to be significant predictors of overall and disease-free survival after complete resection, whereas the Müller-Hermelink and Masaoka classifications were independent significant predictors for overall (p < 0.05) and disease-free survival (p < 0.004; p < 0.0001). CONCLUSIONS: The consideration of staging and histology in thymic tumors has the potential to improve recurrence prediction and patient selection for combined treatment modalities.     

Thymoma needs a new staging system

Despite the wide use of the Masaoka staging system for thymoma, the distribution of survival by stage group is not well balanced. The new staging systems for testing were defined as follows: stage I was created by merging Masaoka's stages I and II, and stage IV remained unchanged. Stages II and III were defined as thymomas with invasive growth and the following combinations of tumor diameter and number of involved structures/organs. Scheme 1: stage II included tumors less than 10 cm in diameter and involving one neighboring structure/organ. Stage III included tumors with all combinations of diameter and number of involved structures/organs other than those in stage II. Scheme 2: stage II included tumors of all combinations other than those in stage III. Stage III included tumors 10 cm or more in diameter and involving two or more structures/organs. The survival curves were assessed for 138 patients treated at the National Cancer Center, Tokyo. The 10-year survival rates for each stage according to the Masaoka, Scheme 1, and Scheme 2 systems were as follows: stage I (100%, 100%, 100%), stage II (100%, 86%, 83%), stage III (70%, 64%, 34%), and stage IV (34%, 34%, 34%), respectively. The survival curves for Scheme 1 gave the most balanced distribution of survival in each staging group. By considering both tumor diameter and number of involved structures/organs, Masaoka's stages I-III could be rearranged with more balanced distribution of survival.