Introduction: In patients receiving opioids, relief of cancer pain by palliative radiation therapy or other means can lead to opioid discontinuation and subsequent withdrawal symptoms, such as agitation, insomnia, and diarrhea, due to opioid-related physical dependence. Appropriate steps should be taken to prevent these symptoms. Case: A 72-year-old man underwent surgery for esophageal cancer. He developed low back pain and right lower limb pain, and was diagnosed with sacral and right iliac bone metastases. His pain was resistant to oxycodone (OXC), so he was simultaneously treated with methadone (MDN) and palliative radiotherapy. His pain gradually decreased, and MDN was tapered and switched to OXC, which was in turn discontinued at 20 mg/day at the patient's strong request. After OXC discontinuation, akathisia, anxiety, and diarrhea appeared as withdrawal symptoms. These were treated with immediate-release OXC, transdermal fentanyl, and suvorexant. Discussion: When discontinuing opioids, dose reduction below 10% per week is recommended, de-escalation to the lowest possible dose should be followed by cessation. In case of withdrawal symptoms, immediate-release opioids may be used, and opioid tapering should be attempted in parallel with symptom control.

Introduction: Intracranial tumors cause various neurological symptoms and neuropathic pain, which are often refractory to opioids. In some of these cases, the combination of Kampo medicines can be effective. Case: The case was a 44-year-old patient who underwent surgery for a suspected papilloma. After resection, pathological examination revealed squamous cell carcinoma, positive for margins, and then, the left intraorbital metastasis was observed. Due to the intracranial invasion of the tumor, he had pain in the second and third branches of the trigeminal nerve in the left face and paresthesia in the second branch of the trigeminal nerve bilaterally (Numerical Rating Scale: NRS 10/10). Hydromorphone was introduced, and the pain was relieved, but the paresthesia remained (NRS 8/10). Both paresthesia and pain worsened during the course of chemotherapy, but MRI showed no tumor progression, thus, the cause of symptom aggravation was diagnosed edema of the tissue around the tumor. Therefore, Goreisan was started, and both paresthesia and pain were relieved. Discussion: Goreisan has been shown to be effective in cerebral edema due to its water-regulating effect by inhibiting aquaporin. In the present case, the reduction of edema in peritumoral tissues by Goreisan may have contributed to the symptomatic relief.