Evidence and controversy for thymectomy in myasthenia gravis

ABSTRACT

Myasthenia gravis (MG) is an acquired autoimmune disease mediated by antibodies against components expressed in the neuromuscular junction. The thymus plays an important role in the development of MG. More than 80% of patients with MG demonstrate histological abnormalities of thymus, such as follicular hyperplasia or thymoma. Although thymectomy is standard treatment for patients with MG who have thymoma, whether the procedure is of any clinical benefit in patients without thymoma has been questioned for more than 40 years. In the 2016 issue of the New England Journal of Medicine, the results of the first randomized trial to assess the role of thymectomy in the treatment of MG, the Thymectomy Trial in Non-Thymomatous Myasthenia Gravis Patients Receiving Prednisone Therapy (MGTX) was reported. The MGTX trial conclusively proved that thymectomy improved clinical outcomes over a three-year period in patients with non-thymomatous MG, which provided Class Ⅰ evidence supporting the use of thymectomy in patients with non thymomatous MG. However, there are still debates on the selection of patients for surgery, and surgical approaching techniques. In addition, the benefit of the thymectomy remains less clear in other subgroups of MG. In the future, randomized controlled trials are required to resolve those controversies and to maximize the benefit of thymectomy in the treatment of MG.