GR01.03 Surgical Oncology

Abstract

In this section we will address the controversial areas of surgical management in the more advanced stages of thymoma. Using case-based discussion we will debate the following clinical scenarios: Stage III Thymic tumours ( with invasion of great vessels) Is there a role for primary surgical debulking leaving an intentional R2 resection? There is little survival evidence to support intentional debulking but such procedures may reduce the dose and extent of radiotherapy subsequently required and therefore the associated morbidity [1]. However, there is a lack of supportive evidence for debulking surgery in thymic carcinoma. [2,3] Should primary treatment be chemoradiotherapy followed by consolidation surgery? Induction therapy is feasible in locally advanced thymic tumours and has been reported to achieve around a 50% partial response. A complete pathological response has not been seen but such treatment can facilitate a high rate (over75%) of R0 resection.[4] Stage IVa Thymic tumours – pleural/pericardial deposits Is there a role for radical surgery? The International Thymic Malignancies Interest Group have recommended that in locally-advanced Stage IVa patients with pleural involvement, major pleural resections, including pleurectomy/decortication or extrapleural pneumonectomy are indicated, provided a complete resection of the pleural deposits is anticipated, usually in a multidisciplinary setting [5] Should this be extrapleural pneumonectomy or thymectomy and extended pleurectomy/decortication? As in other disease, extrapleural pneumonectomy (EPP) is associated with a high 30 day mortality of up to 17% (6). Providing a complete resection can be achieved there is no difference between EPP and extended pleurectomy decortication (EPD) (7] and median survival may exceed 4 years. The contribution of occult nodal metastases must be recognized and radical resection must include lymph node dissection. Stage migration due to lymph node metastases, WHO-classification type C, and T3/4-status are associated with inferior survival but extended surgery has been found to be the only independent significant prognosticator in multivariate analysis [8,9]. Which surgical incision is best? Radical resections can be facilitated by extended approaches which are well tolerated and adequate exposure is necessary to ensure a complete resection Recurrent thymic tumour – after previous resection Is there evidence that extending local control prolongs overall survival over systemic therapy alone? Survival is acceptable and superior to non surgical treatment if complete resection of recurrence is achieved. There is no evidence to support debulking of recurrent thymoma [10] A significant poorer prognosis is associated with multiple versus single relapses, Masaoka stage III primary tumour versus Masaoka stage I-II primary tumour, distant versus loco-regional relapses and B3 histotype versus other. On multivariate analysis, completeness of resection, number of metastases, Masaoka stage of primary tumour and site of relapse were identified as the only independent predictors of prognosis [10] The relative rarity of thymic neoplasms has contributed to the lack of high grade evidence from randomized controlled trials of large numbers of patients. Most supportive evidence for radical surgery in advanced thymic malignancies has therefore been provided by relatively small selected case series. However, the formation of larger collaborative groups with cumulative databases has provided more robust support for extended surgical procedures that many have avoided previously. The superiority of resection as part of multimodality treatment over non-surgical treatment alone seems to be justified provided high quality surgical standards are maintained.