There was a significant decrease (P < 0.01) in the percentage of Nav1.8-positive small neurons in bilateral DRG from the tumor-bearing group accompanied by advanced cancer pain compared to the sham group; the decrease was from 86.9% to 74.0% for the ipsilateral side and to 79.0% for the contralateral side. The gene discussed is SCN10A; the disease is neoplasm.