Thymus gland removal seen as effective option for late-onset MG
Study finds patients who had procedure were more likely to respond to treatment
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- Thymectomy may be an effective treatment option for late-onset MG.
- LOMG patients undergoing thymectomy were more likely to respond to treatment.
- The procedure did not increase surgical complication risks for older patients.
Thymectomy, the surgical removal of the thymus, may be an effective therapeutic option for people with late-onset myasthenia gravis (LOMG) without increasing the risk of surgical complications.
That’s according to a study in China, which also demonstrated that LOMG patients who underwent the surgical procedure were about 2.4 times more likely to achieve treatment response than those treated with medications alone.
The study, “Effects of Thymectomy in Late-Onset Myasthenia Gravis: A Multi-Center Longitudinal Retrospective Study,” was published in Annals of Neurology.
MG is caused by self-reactive antibodies that attack proteins involved in nerve-muscle communication, affecting the muscles that control voluntary movements. Abnormalities in the thymus, an organ of the immune system, are thought to contribute to the production of the self-reactive antibodies that drive MG.
Such abnormalities include thymic hyperplasia (an enlarged gland) or a tumor in the thymus (thymoma). Surgery to remove the thymus may be recommended for MG patients, especially those with a thymoma or with early-onset disease. However, the age limits for thymectomy in MG without thymoma are a matter of debate.
Retrospective analysis compares thymectomy patients with others
The researchers conducted a retrospective analysis of the Clinical Cohort Study of MG, a nationwide, multicenter database. A total of 265 LOMG patients, with a mean age at disease onset of 60.8, were followed for almost four years.
At study enrollment, almost all patients (95.8%) were receiving medications, including prednisone and non-steroid immunosuppressive therapies, with 44.2% receiving both.
Among them, 210 received medical treatment alone, while 55 underwent thymectomy. Those who had surgery were significantly younger than those who were medically treated (56.3 vs. 62). Patients who were younger at disease onset were also more likely to undergo thymectomy.
All patients who underwent thymectomy were matched with 110 patients treated with medications alone, after adjusting for age at disease onset, sex, disease duration, follow-up time, oral medications, bulbar symptoms (such as difficulty swallowing), MG severity, impact on daily life, and coexisting conditions.
The thymectomy-treated group was 2.36 times more likely to achieve minimal manifestation status (MMS) or disease remission. MMS is defined as having no notable functional limitations or symptoms, although some muscle weakness may be present.
Thymectomy also led to a significantly higher treatment response than medications after two years (48.9% vs. 23.8%) and three years (59.5% vs. 28.9%). After five years, the difference remained but was not statistically significant (76.2% vs. 57.9%).
The researchers looked at the adverse effects of thymectomy in 50 patients with LOMG aged 50 and older compared with 49 patients aged 40 to 49. The groups had a similar incidence of adverse events (32% vs. 22.4%), including life-threatening events (10% vs. 8.2%) such as MG crises, in which the respiratory muscles become too weak and ventilatory support is needed.
The “study provides evidence supporting that patients with LOMG can benefit from thymectomy, achieving more favorable outcomes compared to medical treatment alone,” the researchers wrote.
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