Mortality and Cancer Risk in Patients with Myasthenia Gravis (MG): A Retrospective Study
Mohamed Khateb1, David Yarnitsky1, Shahar Shelly1
1Neurology, Rambam Health Care Campus
Objective:
Mortality and cancer risks in MG.
Background:
Patients with autoimmune diseases are considered to have higher risk of developing cancer and vice versa. In MG, an autoimmune disorder affecting the neuromuscular junction, information about prevalence of cancer is lacking mainly due to small number of studies and methodological limitations.
Design/Methods:
We conducted retrospective analysis of all patients diagnosed with MG at a between 2000 and 2023 extracting cancer rates, mortality and clinical features compared to three age-sex matched control groups of neurological, internal or rheumatologic inpatients. The primary outcome was all-cause mortality. The secondary outcome was the incidence of cancer.
Results:
We identified 436 patients with MG diagnosis. Median age at symptoms onset was 64 (range: 5-93 years) for males and 54 (range: 1-87 years) for females. MG symptoms at onset were recorded as ocular (60%, 260/436), strictly bulbar (10%, 45/436) or generalized (23%, 100/436). Median age of death was 79 years (range: 32-107 years) as a group (range: 32-107 years), specifically, 83 years for males (range: 32-107 years) and 79 (44-106 years) for females (p=0.42). Mortality from disease onset at 5 years was 14% (61\422), increasing to 21% (87\422) at 10 years. Mortality was significantly higher compared to the control groups (p<0.001). Cancer data was available in 418 MG patients with 41% (172/418) cancer was documented, specifically 12% (50/418) thymic and 32 % (134/418) extrathymic cancers. Compared to controls, neurology (12.16%, 159/1308), internal medicine (24.38%, 319/1308) or rheumatology (12%, 157/1308), MG patients had significantly higher rates of malignancies, this holds true also after including only extrathymic cancers (p<0.01).
Conclusions:
The data emphasizes the complexities of MG, mortality, and its relationship with cancer. Mortality and extrathymic cancer rates were higher in MG compared to all the controls. More research is needed to determine the exact nature of these relationships.