DREZotomy, which PDR simulates, is an effective way to treat intractable chronic pain, including cancer pain [42], brachial plexus avulsion pain [43], etc. Our results suggest that though DREZotomy still causes pain, its painful intensity is not comparable with the chronic neuropathic pain mentioned above, as pERK1/2 and c-Fos in DRG and DH are less activated by DREZotomy. This evidence concerns the gene FOS and cancer.