Minimally invasive thymectomy for thymoma: does surgical approach matter or is it a question of stage?

Abstract

Complete (R0) surgical resection remains the primary treatment modality for thymoma in both early and advanced stage disease. Following trends seen in surgery for other malignancies, minimally invasive thymectomy (MIT) utilizing VATS or robotic approaches have increased in popularity due to the short term and cosmetic benefits associated with minimally invasive surgery. However, the efficacy of MIT for thymoma compared to open surgery (which utilizes a median sternotomy or thoracotomy) based on oncologic results or survival outcomes remains controversial. The theoretical risk of incomplete resection or capsular disruption causing recurrence and decreased survival with MIT has led many surgeons to avoid MIT for the treatment of thymoma. Because of the relative rarity of the diagnosis and the indolent course of thymoma, comparisons of surgical technique have relied mainly on small single-center retrospective reports which provide limited levels of evidence to support any specific treatment paradigm. Historically, MIT was performed using the transcervical approach popularized as a method for treating myasthenia gravis (MG), not thymoma, although one series does report their experience with the technique for thymic tumors (1). The relative difficulty of transcervical thymectomy compared to VATS or robotic approaches has resulted in the much wider adoption of VATS/Robotic MIT as the preferred minimally invasive approach. Other questions regarding thymoma management such as which staging system to use, how to utilize the World Health Organization (WHO) histologic classification, what induction or adjuvant therapies are indicated and for which stage of disease, and whether partial thymectomy, debulking surgery, or re-operative surgery are beneficial remain unanswered. These issues and the different treatment strategies employed per patient and per institution are important confounding factors whenever one analyzes any particular surgical technique.Open Surgical resection has been the gold standard of treatment for thymoma because the overwhelming majority of thymomas are localized at the time of diagnosis and amenable to local therapy. A comprehensive review of the literature that complied studies that included at least 100 patients revealed that 40% of thymomas presented as stage I, 25% as stage II, 25% stage III, 10% stage IVa, and 1-2% stage IVb (2). Thus 65% of patients presented with disease confined to the thymus gland without invasion into adjacent structures. In that review, the ability to perform an R0 resection for early stage disease was nearly 100% for stage I, with 85% for stage II (range, 43-100%). The average rate of R0 resection rate diminished significantly with advanced stage, only 47% for stage III and 26% for stage IV. In stage III and IV disease, the rate of complete resection varied widely between studies reflecting the heterogeneity of advanced stage thymomas in terms of the degree and location of invasion and the differences in institutional practice patterns concerning aggressiveness of resecti...

Clinicopathological retrospective analysis of thymoma in Serbia: Single center experience

“…Patients in the stage IV manifested similar tendencies, approximately 5-year survival rate of 71% and 10-year survival rates of 47%. This shows that even patients with extensive disease can rich long-term survival rate that are not common in other malignancies 30 . If radical operation cannot be accomplished at the time of surgery (either initially or after neoadjuvant chemotherapy), patients should undergo maximum debulking procedure followed by postoperative chemotherapy/RT 46 .…”

“…Stage of the disease is one of the the main prognostic factors in thymoma patients, as an indicator of operability that represents a therapeutic approach with the highest probability of healing. Kaufman and Flores 30 described that the ability to do radical operation for early stage disease is almost 100%, while in the third and fourth stages of the disease, the radical operation rate fluctuated considerably, depending on the tumor location and degree of inva-sion, as well as the difference in the strategic approaches to radical operation treatment of the medical centers 30 . Our analysis showed that a majority of the patients, nearly one half, were in the stage I, while a remarkable variability in the proportion of stages, as specified by the Masaoka-Koga staging system, was noticed in the stages II, III and IV.…”

Minimally invasive surgery in the management of resectable thymoma: a retrospective analysis from the National Cancer Database

“…Data from these studies are heterogenous at best in that it included resections of benign or involuted thymus for symptomatic control of Myasthenia Gravis (14-28). However, few reports exist to determine whether minimally-invasive techniques have similar efficacy as sternotomy when looking at oncologic determinants such as operative margins (5,6,28,29). To this end, the NCDB provides a robust patient population for comparison.…”

“…Minimally invasive surgery in the management of resectable thymoma: a retrospective analysis from the National Cancer Database include median sternotomy, clamshell, thoracoscopy, and robot-assisted. The latter methods (i.e., minimallyinvasive thymectomy) have gained increasing popularity due to reports of shorter length of stay (LOS), decreased post-operative pain, and lower operative blood loss (5). However, few reports exist on the oncologic efficacy of thoracoscopic or robotic approaches in the treatment of thymomatous tumors (6).…”

Contemporary treatment for thymic malignancies: what’s the bottom line?

“…But there have been numerous reports and case series which have shown good outcomes when resecting large anterior mediastinal masses using minimally invasive approaches (3,4). In experienced centers, these large tumors can be resected using minimally invasive approaches with no differences in rates of R0 resection, perioperative complication rate (5,6) and with a low conversion rate (7). Surgeons should individualize each case and use their comfort levels with minimally invasive techniques when deciding whether a tumor can be completely resected by VATS or RATS.…”