Lambert-Eaton syndrome (LES) is an immune-mediated disorder of the presynaptic 
neuromuscular junction due to the blocking effect of the voltage-gated calcium 
channel (VGCC) antibodies. Small-cell lung cancer (SCLC) is the most common 
cause of LES. We report an unusual case of LES associated with large-cell 
neuroendocrine carcinoma (LCNEC) of the lung. In this case, clinical symptoms of 
LES predated the diagnosis of LCNEC by 6 years. After tumor resection, the 
patient experienced clinical and electrophysiological improvement. In addition, 
he had a decrease in VGCC antibody titer from 130 to 80 pmol/L. The onset of LES 
can be prolonged, and tumor surveillance should continue in these cases.