Randomized Trial of Thymectomy in Myasthenia Gravis

The first reported use of thymectomy in patients with nonthymomatous myasthenia gravis was 75 years ago.1 Of six patients who underwent surgery, three had a favorable response. Subsequent retrospective studies have shown benefits of thymectomy in patients with nonthymomatous myasthenia gravis but with widely varying rates of clinical improvement or remission. A compilation of retrospective studies comparing surgery with medical management did not show a difference in remission rates.2 Two studies that showed clinical improvements after thymectomy indicated that benefit occurred in the first few years after the procedure, but after 5 years, rates of clinical improvement were similar among surgically treated patients and those who were treated medically.3,4 Observational studies have not shown benefits of thymectomy, perhaps because of the effectiveness of modern immunotherapeutic approaches.5

Despite calls for a randomized, controlled study, data are lacking, and uncertainty persists regarding the benefit of thymectomy and the clinical characteristics of the patients who should be offered the procedure.6,7 A systematic review8 of articles describing outcomes in 21 cohorts of patients with myasthenia gravis pointed out numerous methodologic flaws that prevented definite conclusions to be drawn regarding the benefits of thymectomy in patients with nonthymomatous myasthenia gravis.

Glucocorticoids have been widely used for the treatment of myasthenia gravis either as the sole therapy or with thymectomy.9 Although adverse effects are not common with thymectomy, the procedure can cost up to $80,00010 and can be associated with operative complications that need to be weighed against benefits. Glucocorticoids and other immunosuppressive agents place patients at risk for adverse events, some of which are life-threatening, and affect quality of life. Therefore, establishing the role of thymectomy in patients receiving glucocorticoids to manage myasthenia gravis would guide decisions regarding treatment and the costs of health care.

We conducted the Thymectomy Trial in Non-Thymomatous Myasthenia Gravis Patients Receiving Prednisone Therapy (MGTX), an international, randomized, single-blind (rater-blinded) trial, to determine whether extended transsternal thymectomy combined with a standardized prednisone protocol would be superior to prednisone alone after 3 years, with respect to lessening myasthenic weakness, lowering the total dose of prednisone, and enhancing quality of life. Extended transsternal thymectomy was chosen because it provides reproducible resection of the maximal amount of thymic tissue with low morbidity and a limited risk of phrenic-nerve injury.11

click here for more info in the Trial Methods and Results

Article by: The New England Journal of Medicine