Thymectomy benefits older gMG patients without a thymus tumor
Surgery to remove gland also helps reduce daily corticosteroid doses
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- Thymectomy surgery effectively manages generalized myasthenia gravis in both younger and older patients, a study found.
- The study included patients who did not have a thymus tumor.
- The surgery to remove the thymus gland also reduced reliance on immunosuppressive medications.
Thymectomy — a surgery to remove the thymus gland — can help keep generalized myasthenia gravis (gMG) under control while decreasing the need for immunosuppressive medications in both younger and older patients without a thymus tumor, a study found.
“These findings provide some support to the use of thymectomy in the management of older patients with MG,” researchers wrote in “A comparison study of thymectomy outcomes in young and older patients with non-thymomatous myasthenia gravis,” which was published in the Journal of Neurology.
Earlier study found thymectomy benefitted younger patients
In MG, self-reactive antibodies mistakenly attack proteins involved in nerve-muscle communication, causing symptoms such as muscle weakness and fatigue. In many MG patients, this autoimmune response is linked to abnormalities in the thymus, including a thymoma, which is a tumor that grows from cells of that small gland.
A thymectomy is often recommended for treating MG in patients who have a thymoma because it can reduce the production of antibodies, including self-reactive ones. An earlier clinical trial, called MGTX (NCT00294658), showed that this type of surgery can also benefit patients with non-thymomatous MG, that is, MG without a thymoma. However, data came mainly from patients younger than 50.
To understand whether benefits also apply to older patients, the researchers looked at whether a thymectomy is as effective and safe in adults age 50 or older as it is in younger adults with non-thymomatous gMG. This common form of the disease is marked by weakness affecting muscle groups throughout the body.
The researchers retrospectively reviewed the medical records of 79 adults with non-thymomatous gMG who underwent a thymectomy at Cleveland Clinic Foundation between 1999 and 2022.
A total of 34 patients (43%) were 50 or older, and 45 (57%) were younger than 50. Most (78.5%) had self-reactive antibodies against the acetylcholine receptor protein, the most common type of MG-driving antibody.
Compared with younger patients, older patients were significantly older at diagnosis (mean of 60.3 years vs. 31.7 years) and were significantly less likely to be women (38.2% vs. 82.2%).
The older group also showed significantly higher rates of minimally invasive thymectomy (82.4% vs. 60%) and significantly lower rates of thymic enlargement (26.5% vs. 73.3%).
Younger, older patients showed improvement in symptom severity
After the thymectomy, both groups showed improvement in the Myasthenia Gravis Foundation of America classification, which grades how severe symptoms are and how much the disease affects different body functions. The proportion of people experiencing improvement was similar between the two age groups at six, 12, and 24 months and at the final follow-up.
The number of post-surgery exacerbations, which are episodes of sudden symptom worsening, was also similar between the two age groups. The need for rescue treatments, such as intravenous immunoglobulin, which provides healthy antibodies through a vein, or plasmapheresis, which removes disease-causing antibodies from the blood, was also not significantly different between the groups.
People in both groups also had similar scores on the MG Activities of Daily Living scale, which assesses the disease’s impact on everyday activities such as eating, speaking, breathing, and walking. A similar percentage of older and younger patients achieved minimal symptom expression, meaning they had very few or no symptoms (55.9% vs. 44.4%, respectively).
The percentage of patients who reduced their daily dose of corticosteroids by at least 10% was also similar between the groups at all time points evaluated. Corticosteroids work by suppressing the immune system but can cause serious side effects when used at high doses or for too long.
At the final follow-up, about half of patients (44% in the older group vs. 49% in the younger group) were taking 5 mg or less of the corticosteroid prednisone daily without additional immunosuppressive therapies.
The safety and efficacy of thymectomy in those aged 50 or older with non-thymomatous MG appear comparable to that of their younger counterparts.
Among participants on non-corticosteroid immunosuppressants, most of those in the younger group (75%) discontinued this type of treatment, while none of those in the older group did so.
More than one month after surgery, complications, including abnormal heart rhythm, infection at the surgical site, and blood clot-related adverse events, occurred at similar rates in younger and older patients. There were also no significant differences between the two groups in the development of new autoimmune diseases or non-skin cancers.
Overall, “the safety and efficacy of thymectomy in those aged 50 or older with non-thymomatous MG appear comparable to that of their younger counterparts,” the researchers wrote.
Although the study was relatively small and based on past medical records, its findings support considering thymectomy as a treatment option for appropriately selected older non-thymomatous gMG patients.
“Our study is exploratory, and well-conducted, well-matched … prospective studies [performed forward in time] including older patients who did not undergo thymectomy — similar to the MGTX trial — are needed to further clarify the role of thymectomy in older patients with non-thymomatous MG,” the researchers wrote.
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