Dr Leal on Clinical Considerations Surrounding the Diagnosis of LEMS in Patients With Lung Cancer

“As a medical oncologist, seeing patients with SCLC or [potentially] NSCLC, the critical thing is to think about the clinical presentation of LEMS. There needs to be awareness and education on the symptoms, because sometimes the symptoms can be vague at initial onset, and that can delay diagnosis or [lead to] misdiagnosis, especially in somebody with SCLC who may already have deconditioning.”

Ticiana Leal, MD, a professor and director of the Thoracic Medical Oncology Program in the Department of Hematology and Medical Oncology at Emory University School of Medicine, as well as medical director of the Clinical Trials Office at Winship Cancer Institute, outlined key considerations for medical oncologists in recognizing and diagnosing Lambert-Eaton myasthenic syndrome (LEMS), particularly in the context of small cell lung cancer (SCLC) and, in rarer cases, non–small cell lung cancer (NSCLC).

She emphasized that timely identification of LEMS is critical, as early symptoms may be subtle and easily attributed to cancer-related deconditioning or treatment effects, leading to missed or delayed diagnosis. Leal underscored the need for oncologists to maintain a high index of suspicion when evaluating patients with neuromuscular symptoms.

LEMS often presents with a clinical triad consisting of proximal muscle weakness, dysautonomia, and areflexia or hyporeflexia. Proximal weakness, particularly when out of proportion to the patient’s disease burden or functional status, should prompt consideration of LEMS. Leal stressed that some symptoms may be mistakenly attributed to systemic illness or chemotherapy-related fatigue, highlighting the importance of clinician awareness.

Once LEMS is suspected, a thorough neurologic examination is essential, followed by confirmatory diagnostic testing. Leal explained the importance of ordering voltage-gated calcium channel (VGCC) antibody testing, which is highly specific for LEMS and can confirm the diagnosis in the majority of cases. She noted that VGCC testing should be pursued promptly whenever clinical suspicion arises.