From the Guidelines
Yes, patients with myasthenia gravis can develop cancer, particularly a type called thymoma, with approximately 30% to 50% of patients with thymomas having myasthenia gravis. The association between myasthenia gravis and thymoma is well-established, with thymoma being a tumor of the thymus gland [ 1 ]. Additionally, myasthenia gravis can occur as a paraneoplastic syndrome, meaning it develops as a result of an immune response to cancer elsewhere in the body. This association is known as a paraneoplastic neurological disorder.
Key Points
- Patients with myasthenia gravis are at risk for having or developing thymoma [ 1 ].
- Thymectomy is indicated in the presence of thymoma, and may also be beneficial for specific age-based and immune-based characteristics to reduce clinical symptoms [ 1 ].
- Chest imaging, typically CT scan, is recommended as part of the initial evaluation for newly diagnosed myasthenia gravis patients to screen for thymoma [ 1 ].
- Regular cancer screening appropriate for age and risk factors remains important for myasthenia gravis patients, as they can develop the same cancers as the general population.
Management
- Surgical removal of thymoma (thymectomy) is typically recommended for cancer treatment and to improve myasthenia symptoms [ 1 ].
- Patients with myasthenia gravis should be evaluated for thymoma, and those with thymoma should receive treatment by a multidisciplinary team, including a neurologist and an oncologist [ 1 ].
From the Research
Association between Myasthenia Gravis and Cancer
- Patients with myasthenia gravis (MG) can have cancer, with studies indicating a potential link between the two conditions 2, 3, 4.
- The co-existence of MG with extrathymic malignancies has been reported, with older age of MG onset being a risk factor for development of malignancy in MG 2.
- Thymoma, a type of tumor, is associated with MG in approximately 15% of patients, and screening for thymoma is recommended at the onset of MG or when patients present with clinical deterioration 5.
Risk Factors for Cancer in Myasthenia Gravis Patients
- Older age, thymoma, and immunoglobulin use have been identified as risk factors for extrathymic neoplasms in patients with MG 3.
- The use of corticosteroid-sparing immunosuppressants (CSISs) has been linked to an increased frequency of cancer, particularly in patients with thymoma-associated MG (TAMG) and late-onset MG (LOMG) 4.
- Azathioprine treatment has been thought to have a potential risk for developing secondary malignancies in MG patients, but a systematic review and meta-analysis found no significantly elevated risk of cancer occurrence among individuals with prior MG diagnosis who received long-term azathioprine treatment 6.
Cancer Types and Myasthenia Gravis Subtypes
- Extrathymic cancers are common in MG patients, with skin cancer and cancer in the male genital organs being the most common types 4.
- Patients with TAMG and LOMG have the highest occurrence of extrathymic cancer, with cancer frequency being comparable between acetylcholine receptor antibody seropositive and seronegative patients 4.