Recently, our department adopted spinal dorsal root medullary incision to relieve the pain of two patients with neuropathic pain in the perineal region, buttocks and posterior thighs caused by rectal cancer sacral metastasis invading sacral nerve. Cancer pain caused by tumor can be divided into 2 categories: 1. sensory injury pain: this kind of pain can be divided into visceral pain and sensory injury pain of somatosensory nervous system according to the location of pain, if drug treatment is ineffective, posterior median spinal cord dissection or intrathecal drug pump implantation can be used according to the location of pain, and pain can be controlled by infusion of morphine and other drugs in subarachnoid space; 2. neuropathic pain: this kind of pain is mostly caused by tumor invasion of nerves. This kind of pain is mostly caused by tumor invasion of nerve, which often manifests as intractable burning, stabbing or cutting pain in the nerve damaged area, accompanied by loss of skin sensation and corresponding neurological impairment symptoms.