Patients with Lambert-Eaton myasthenic syndrome (LEMS) live as long as people who do not have the disease, and can lead a relatively normal life despite having some physical limitations, a study contends.
The study, “Long‐term follow‐up, quality of life, and survival of patients with Lambert‐Eaton myasthenic syndrome,” was published in the journal Neurology.
LEMS is a rare autoimmune disease that affects the neuromuscular junction — the place where motor neurons and muscle fibers communicate — leading to muscle weakness, reduced reflexes, and high fatigue.
The disorder often is associated with cancer, as 50% t0 60% of all patients with LEMS have an underlying tumor. The most frequent type of malignancy seen among those with LEMS is a type of lung cancer called small cell lung cancer (SCLC), which accounts for about 15% of all lung cancer cases.
“Limited data suggest some improvement of symptoms in patients with LEMS with SCLC (SCLC-LEMS) after treatment of the tumor,” researchers said.
Although previous studies have suggested the survival of those with SCLC-LEMS may increase following cancer treatment, “no data exist on the quality of life of this period of improved survival,” researchers stated in the study. In addition, data on the survival and quality of life of those with LEMS who do not have associated tumors also is very limited.
To tackle these questions, researchers from thedocumented the survival, health-related quality of life (HRQoL) and long-term functional impairments of patients with LEMS with and without associated tumors.
The observational study included data from 150 Dutch patients with LEMS. Of these, 85 (57%) had an associated lung cancer tumor (PNS-LEMS) and 65 (43%) did not (NT-LEMS).
Survival, HRQoL and the degree of functional impairments seen among those with LEMS were compared to data from individuals from the general population who had neither LEMS nor any type of cancer, and also to SCLC patients who did not have LEMS (non-LEMS SCLC).
After adjusting data for age, sex and year of diagnosis, researchers found the life expectancy of those with NT-LEMS was similar to the average life expectancy of individuals from the general Dutch population.
In addition, they found that those with SCLC-LEMS lived longer than those with non-LEMS SCLC (median survival of 17 versus seven months), even after adjusting the data for tumor stage.
Detailed one-year follow-up data on functional impairments was available for 63 patients with LEMS (41 with NT-LEMS and 22 with SCLC-LEMS). At diagnosis, 39 patients (62%) with LEMS were considered self-care independent (KPS score higher than 70). The percentage of those who were able to carry activities of daily living independently rose to 85% after one year.
A total of 44 patients with LEMS (66%) completed the SF-36 questionnaire. The physical composite score of HRQoL was found to be significantly lower among those with LEMS (55.9) compared to individuals from the general population who did not have LEMS (76.3), and more similar to that of patients with myasthenia gravis (MG) (60.5).
In contrast, the mental composite score of HRQoL was identical in patients with LEMS (71.8), MG (70.3) and individuals from the general population (77.9).
“This study shows that patients with LEMS without an associated tumor have a normal survival, confirms that patients with SCLC-LEMS have an improved tumor survival com pared to patients with SCLC without LEMS, and shows that patients with LEMS can have a relatively well-controlled life with mainly physical limitations and normal mental quality of life,” the investigators wrote.
“[These findings] can guide expectations of doctors and patients and be of potential relevance for treatment choices,” they stated.