Exploring the Underreporting of Lambert-eaton Myasthenic Syndrome in Small Cell Lung Cancer
Laura Hidalgo1, Chelsea Chang1, Nicholas Streicher2
1Georgetown University School of Medicine, 2Neurology, Georgetown University School of Medicine
Objective:
This study evaluates Lambert-Eaton Myasthenic Syndrome (LEMS) prevalence in a cohort of small cell lung cancer (SCLC) patients to assess underrecognition.
Background:
LEMS is a neuromuscular disorder caused by autoantibodies against presynaptic voltage-gated calcium channels, resulting in proximal weakness, autonomic dysfunction, and hyporeflexia. Approximately 3-4% of SCLC patients are estimated to have LEMS (Elrington et al., 1991; Gozzard et al., 2015; Soomro et al., 2020), yet reported cases remain fewer. Underreporting may stem from symptom overlap with cancer effects, limited clinician awareness, and diagnostic challenges.
Design/Methods:
We retrospectively reviewed records from a large academic center between January 2010 and December 2022. SCLC patients were identified via ICD-10 codes or chemotherapy regimens including etoposide or cisplatin. LEMS cases were identified through ICD-10 codes or positive P/Q-type voltage-gated calcium channel antibodies. Data included demographics, symptom onset, severity, and comorbidities. Observed prevalence was compared to expected rates from prior literature.
Results:
Among 564 SCLC patients, only two (0.35%) had a recorded LEMS diagnosis. This is nearly tenfold lower than the expected 3-4% prevalence, indicating substantial underreporting. LEMS was documented in 14 patients overall, with 50% associated with malignancy. The combined prevalence in SCLC and NSCLC patients was 35.7%, but disproportionately few were identified among SCLC cases. Prior studies estimate LEMS prevalence in SCLC at 3-4% (Elrington et al., 1991; Gozzard et al., 2015), and prospective studies with systematic neurologic assessment confirm higher rates than typically reported (Soomro et al., 2020; Jayarangaiah et al., 2023).
Conclusions:
These findings highlight underrecognition of LEMS in SCLC, likely due to overlapping symptoms and diagnostic barriers. Misattribution to cancer-related effects or lack of clinician awareness may delay diagnosis. As LEMS can precede SCLC, improved screening and routine neurologic assessments are needed to enable earlier cancer detection and treatment. Raising oncologist awareness is essential to bridge this diagnostic gap.
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