Neurological outcomes of extended thymectomy for thymomatous myasthenia gravis: Subxiphoid vs. trans-sternal approaches

Perspectives on surgical treatment for thymic epithelial tumors: a narrative review

Background and Objective

Thymic epithelial tumors are relatively rare; thus, mostly retrospective studies and a few prospective randomized controlled trials have been conducted on the treatment and the biomarkers, with no standard therapy established. Indications for extended thymectomy, robot-assisted thoracic surgery, and multidisciplinary treatment are controversial. Here, we considered the prospects of surgical treatment and the possibility of immune checkpoint inhibitor (ICI) treatment for thymic epithelial tumors.

Methods

This is a narrative review; PubMed was searched using a set of keywords related to thymoma and its proposed treatments over the last 5 years.

Key Content and Findings

Thymic epithelial tumors are associated with autoimmune diseases. They are relatively rare, and their pathology remains unclear. Therefore, accumulating more case reports is important. Surgical resection is generally considered for both diagnosis and treatment. If the tumor has a strong tendency to invade surrounding areas, such as thymic carcinoma/thymoma, the diagnosis may be confirmed preoperatively by needle biopsy, and induction chemotherapy may be selected. Surgical resection is the most effective treatment, and complete resection is important. In cases where complete resection is difficult, multidisciplinary treatment is performed. Although there are various obstacles, using ICIs may prove effective for treatment both as preoperative and postoperative chemotherapy in the future, as shown for other cancers. Programmed cell death-ligand 1 (PD-L1) is an immunoinhibitory molecule that suppresses T cells activation, leading to tumor progression. Overexpression of PD-L1 in some cancers is associated with poor clinical outcomes. However, the role of PD-L1 expression as a prognostic factor remains controversial. Therefore, various biomarkers other than PD-L1 have been identified.

Conclusions

We reviewed the latest treatments for thymic epithelial tumors. If new therapeutic agents such as ICIs and molecular-targeted drugs are developed, this review suggests that surgery will become more important not only as therapy but also as part of multidisciplinary treatment that includes tissue collection.

Is a subxiphoid approach equivalent to midline sternotomy for extended thymectomy for achieving disease remission in patients with myasthenia gravis?

A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was 'In patients with myasthenia gravis undergoing extended thymectomy, is a subxiphoid approach equivalent to midline sternotomy for achieving disease remission?' Altogether 106 papers were found using the reported search, of which 5 represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. Five studies of a total of 803 patients with myasthenia gravis (MG) reported their experience with thymectomy by subxiphoid approach versus thymectomy by midline sternotomy. These studies demonstrated shorter operation duration, reduced intraoperative blood loss, reduced hospital length of stay and lower postoperative pain scores in the subxiphoid group. There was no significant difference in rates of postoperative MG crisis between the 2 groups, and similar rates of improvement in quantitative myasthenia gravis scores. We conclude that while further high-quality research is required, thymectomy by subxiphoid approach for MG may be considered in preference to midline sternotomy due to improved short-term postoperative outcomes and similar disease remission rates.