LEMS Natural History: Recognizing Symptoms Before a Small Cell Diagnosis

"LEMS Natural History: Recognizing Symptoms Before a Small Cell Diagnosis" takes up the question of timing between LEMS symptoms and the underlying cancer diagnosis.

Dr. Iams opens by noting that LEMS can sometimes be observed clinically before small cell lung cancer (SCLC) is diagnosed, with paraneoplastic symptoms appearing ahead of a histologic cancer diagnosis. Dr. Patel says he has rarely seen LEMS formally diagnosed before SCLC, but more commonly the cancer is diagnosed first, and only when a history is taken afterward does it become clear that LEMS symptoms actually predated the SCLC diagnosis, and even predated typical thoracic symptoms. That realization, he says, often reveals the syndrome had been brewing undiagnosed for some time, which he considers a fairly common pattern in LEMS associated with SCLC. Dr. Iams adds that claims-database data on timing, while imperfect, show an S-curve: a small uptick in LEMS diagnoses before the SCLC diagnosis, a concentration of diagnoses occurring near simultaneously, and continued diagnoses afterward as patients move through treatment. He asks what symptom triggers most commonly prompt Dr. Patel to suspect LEMS in practice. Dr. Patel says experience treating enough SCLC patients helps him recognize when something is off, particularly weakness that exceeds what SCLC alone would explain. He distinguishes ordinary cancer-related fatigue from more specific findings, such as being unable to make a fist, perform a bicep curl, or rise unassisted from a seated position. He also looks at diminished reflexes and cranial nerve findings in the muscles they innervate as further clues that a paraneoplastic process may be present. Once those signs appear, he says, the next step is straightforward: a VGCC antibody test, which he describes as a fairly easy blood test to order, depending on what laboratory access is available at a given practice.

Up next, in "Ordering VGCC Testing and Navigating NCCN Guidelines for LEMS," Dr. Patel and Dr. Iams walk through exactly how to order that VGCC test and where it fits within the latest NCCN guidance.