Marked under-diagnosis of Lambert-Eaton myasthenic syndrome (LEMS) in small cell lung cancer: An analysis of real-world claims data

In this OncLive Rapid Readout, David M. Waterhouse, MD, MPH, of Oncology Hematology Care in Cincinnati, Ohio, reviews findings from a real-world claims analysis evaluating the diagnosis of Lambert-Eaton myasthenic syndrome (LEMS) among patients with small cell lung cancer (SCLC). The study found that LEMS was identified in fewer than 0.3% of patients with presumed SCLC, far below the approximately 3% prevalence reported in prospective studies, suggesting that most SCLC-associated cases remain undiagnosed in contemporary oncology practice. Waterhouse discusses why nonspecific symptoms such as proximal muscle weakness, autonomic dysfunction, and areflexia may be misattributed to cancer, chemotherapy, or supportive medications, contributing to delayed neurologic evaluation and testing. The presentation highlights the clinical implications of missed LEMS diagnoses, including avoidable morbidity despite available therapies, and emphasizes the need for greater oncology awareness, timely referral, and targeted efforts to improve recognition of this paraneoplastic disorder.