Thymectomy is effective for patients with MG without thoracic tumor

Thymectomy combined with Prednisone therapy in patients with non-thymomatous myasthenia gravis (without thymus tumor) resulted in better outcomes for three-year-old patients than steroid therapy alone in a randomized trial, the researchers reported here.

MG is a rare autoimmune disease resulting from an interruption of communication between the nerve and muscle. Patients may develop a variety of symptoms, including drooping eyelids, blurred vision, muscle weakness, and difficulty speaking, swallowing, and breathing. It is estimated that the disease affects about 60,000 Americans.

Research since the late 19th century has suggested that MG is associated with various abnormalities of the thymus gland, and the first use of thymectomy in patients with nonthymomatous myasthenia gravis was reported by Alfred Blalock, MD, and colleagues in the Journal of the American Medical Association in 1941. As reported in that article, of the six patients who underwent surgery, three had a favorable response.

“Since the Blalock report, thymectomy has been used, but there has always been a question of what to get out of it,” said Gil I. Wolfe, MD, of the University of Buffalo Jacobs School of Medicine and Biomedical Sciences and lead author A journal of the New England Journal of Medicine reporting on the randomized trial. Wolfe summarized the trial results in a plenary session here at the annual meeting of the American Academy of Neurology.

“This was a trial that was 15 years in the making and designed to address an issue that has persisted for 75 years,” Wolfe said.
According to Wolfe, although a consensus has been established in favor of thymectomy among this group of patients, “that consensus is based on non-randomized series of cases and there is no evidence of class one or class two.” And although the calls for randomized trials have been repeated, they have never materialized.

Wolfe also noted – based on the national sample of hospitals in about 1,000 hospitals – that the thymectomy rate fell from 7% to 1.5% between 2000 and 2005, suggesting that doctors and patients may have been waiting for See the results of this trial o Due to the availability of alternative therapies for MG.

In this trial, Wolfe and colleagues addressed three questions: Compared to a prednisone protocol alone, thymectomy plus prednisone treatment resulted in:

  • Greater strength improvement (as measured by a weighted mean score of myasthenia severity score)
  • A lower requirement for prednisone
  • Better life quality

Patients 18 to 65 years of age who had generalized non-thymomatous MG with a disease duration of less than five years were included in the trial if they had Myasthenia Gravis Foundation of American Class II-IV disease. A total of 126 patients were included in the study and randomized from 2006 to 2012 to undergo thymectomy plus the standardized prednisone protocol or to receive that steroid regimen alone.

Wolfe and colleagues found that patients undergoing thymectomy had a lower time-weighted mean score of myasthenia gravis over a three-year period than those who received prednisone alone (6.15 vs 8.99) and also needed a third less prednisone to control their disease.
Wolfe and colleagues also found no significant differences between the two treatment groups regarding treatment-related complications but found that patients undergoing thymectomy had fewer treatment-related symptoms associated with immunosuppressive drugs and lower levels of relief related to the symptoms.

“We also say benefits across several subgroups – by age, sex and prednisone exposure – too,” added Wolfe.

“This is a class-one evidence that extended transsternal thymectomy has a favorable impact on the positive MG generated by acetylcholine receptor antibodies, based on clinical outcomes, through quantitative MG score, corticosteroid exposure and Adverse events, ” Wolfe concluded.