1. Overview of palliative medicine Over the next 10 years, major changes in the cure rates for people with cancer and AIDS are not expected to occur, and it is an indisputable fact that many still incurable diseases cause intense suffering. Palliative medicine is concerned with the control of life-long intractable pain such as AIDS and neuropathic pain, in addition to patients with advanced cancer. Because the infectious nature of AIDS and the unidimensional nature of neuropathic pain are very different from the presentation of advanced cancer patients, the principles of health care intervention are very different, and palliative medicine as it is commonly referred to is only for patients with advanced cancer. It is now recognized that the greatest needs of patients at the end of life are comfort, dignity, a sense of usefulness during the life course, and respect for their personhood and reaffirmation of life. Therefore palliative medicine preserves life without delaying the life course of the dying patient. Every advanced cancer patient is recognized as having somatic, psychospiritual, social and religious needs and other problematic needs, each of which should be given full and equal attention. Tracheotomy and lasers to relieve dyspnea, i.e., to become palliative care for advanced bronchial obstruction, surgical stents to relieve biliary and ureteral obstruction, radiofrequency ablation and chemotherapy to necrose or shrink the cancer mass that is causing the symptoms, and radiation to relieve metastatic pain to the bone or the sensation of suffocation in patients with superior vena cava obstruction, etc., are all elements of palliative care. They have the potential to relieve pain and improve the quality of remaining life, rather than being motivated by an attempt to force prolongation or shortening of life. 2. Overview of pain in patients with advanced cancer Most cancers occur in older patients, but death at age 35 and death at age 70 may have similar levels of pain. Of 218 patients with progressive cancer in southern Israel, 77% had actual pain, 75% of whom were treated with medication, but 81% were treated inappropriately, and 64% had moderate to severe limitations in their lives. The results also showed differences in how patients’ pain was evaluated by different investigators, e.g., internists usually overestimated the level of pain but underestimated the impact on daily life. Complex pain must be evaluated in order to optimize treatment. A survey in Kentucky, USA, showed that 71% of 141 patients with advanced cancer complained of pain in the month prior to the survey, 158 significant pain points in 100, and 88% complained of up to 2 pain points. Pain caused by the tumor itself was the most common cause (68%). The nature of pain was 48% of continuous pain and 52% of intermittent pain. 75% of continuous pain had penetrating pain episodes, 30% of these people had frequent episodes, 26% had occasional episodes, 16% had continuous episodes, and 16% had episodes at the end of the drug dosage; 61% of patients with intermittent pain had frequent penetrating pain episodes. 3.Methods of controlling cancer pain Advanced cancer pain patients’ body gradually fails, mostly accompanied by severe pain and anxiety, and thus aggravate loss of appetite, poor sleep, and other dysfunctions of the body to form a vicious circle, accelerating the death. Therefore, pain relief is the key to improve the quality of life. The problem of advanced cancer pain control is complex, and polypharmacy is used in the treatment to mitigate the side effects. Pharmacologic analgesia has an important place in the comprehensive management of cancer pain patients and can provide relief in 85% of cancer pain. Successful management is mainly based on the World Health Organization’s three-step medication guidelines. Pharmacologic pain relief has a dual effect on quality of life as does chemotherapy due to the side effects of all types of drugs. Effective clinical adjustments include: administering drugs at the right time, clinical pain intensification from 23:00 pm to 3:00 am in the morning, adding drugs half an hour before the onset of pain is more effective; necessary suggestive therapy is not only for pain relief, but also for terminal pain; actively dealing with symptoms associated with advanced cancer and other concurrent illnesses such as loss of appetite, nausea and vomiting, dyspnea, hoarseness, coughing, urinary difficulties, constipation, and other Symptoms; psychotherapy such as talking and soothing can promote medication for pain relief. Duke Dickerson on five continents, 25 countries, 50 physicians to do a questionnaire survey, the recognition rate is higher than 16% commonly used in palliative care of the basic drugs are 14 categories of 20 kinds. These drugs are opioid analgesics: morphine (normal release), morphine extended-release, patch fentanyl, methadone, codeine; non-opioid analgesics: paracetamol, diclofenac, tramadol; antiemetic: meprobamate; phenyl tranquilizers anxiolytic: midazolam, valium; corticosteroids: dexamethasone; laxative: lactulose, senna; antipsychotics: haloperidol; antidepressants: amitriptyline Anticonvulsants: clonidine; antispasmodics: scopolamine butylbromide; antifungals: mycophenolate mofetil; progestogens: medroxyprogesterone acetate; and slightly less well recognized drugs are the H2 antagonist: ranitidine; and the antihistamine: xylazine. The core medications thus recommended for pain control are the combination of extended-release morphine, methadone, amitriptyline, and diclofenac. Many patients treated with opioids may still experience a condition known as “prodromal pain”. Additional doses of 10-20% of the daily total can relieve this pain. Light laxatives are routinely prescribed with opioid analgesics, and Valium is often used as an adjunct to morphine for the treatment of painful skeletal muscle spasms. The development of different routes of morphine administration is also a clinical necessity, and rectal administration of long-acting stabilized-release morphine tablets has been reported to achieve excellent results in a 72-year-old patient with prostate cancer. Adverse effects of fentanyl transdermal patches include nausea, vomiting, dizziness, and constipation, most of which resolve with time. Mirex can be given to prevent nausea and vomiting, and in severe cases, the use of central antiemetic drugs (e.g., endansetron hydrochloride) is effective. Mild constipation is usually improved by drinking more water, eating more fiber foods, and being more active. In severe cases, it is effective with the use of light laxatives (e.g. senna, fruit guide tablets). Methadone is considered a good alternative to ยต-opioid agonists with good oral and rectal absorption, high analgesic efficacy at low cost, no accumulation of active metabolites in patients with renal failure, and control potential for pain unresponsive to morphine, hydromorphone, and fentanyl. Eighty to ninety percent of patients with advanced cancer have cachexia and anorexia, and most patients improve with progesterone, dexamethasone, prednisone, dronabinol, and meprobamate. When end-stage disease has two or more symptoms, the most popular from the type of medication considered are antipsychotics, especially haloperidol, which treats prosopagnosia and stops vomiting. Haloperidol is the drug of choice for controlling nausea and vomiting induced by opioids, radiation therapy, and most chemotherapy. Nonsteroidal anti-inflammatory drugs (NSAIDs) may be very useful when pain involves an inflammatory process, especially pain involving bone, muscle, and soft tissue. Patients with metastatic bone disease also require a combination of opioids and NSAIDs for symptomatic relief. Effective pain control requires a multidisciplinary approach to management. A survey of palliative medicine practitioners in Scotland showed that the more socially underdeveloped an area is, the more there is a lack of formal experience of managing patients with cancer pain and a proper attitude to palliative medicine counseling. Approximately 8% of cancer patients have intractable pain and require anesthesia-related therapeutic techniques to manage their pain for optimal outcome. 72% of respondents felt that anesthesiologists provide the necessary skills and that more consultation with anesthesiologists would be beneficial. However, in practice, more than half of the respondents used anesthesia techniques to manage pain less than four times in a year, and one-fourth did not work with an anesthesiologist on pain management in a year. Subarachnoid anhydrous ethanol, phenol-glycerol block or epidural injection block are nerve-destructive approaches that are effective in controlling most cancer pain. For cancer pain that is limited in scope, nerve-destroying agents can be applied to selectively block the nerve roots and nerve trunks associated with it to relieve cancer pain. All of these techniques can significantly reduce the amount of systemic opioid medication, but all require an experienced anesthesiologist to operate. Abdominal plexus ethanol blocks are particularly effective for pancreatic cancer pain. Sympathetic ganglion blocks are effective for bone metastasis pain in the appropriate area. All of these maneuvers need to be performed under x-ray fluoroscopy. Permanent placement of a microcomputerized pump for opioid subarachnoid block is costly but very effective, and is especially valuable for intractable cancer pain where all conventional methods are unsatisfactory. Continuous injection of drugs into the epidural cavity to control cancer pain is also becoming more and more widespread. Using patient-controlled analgesia (PCA) pump or slow-release pump to inject morphine, fentanyl, tramadol and other drugs into the epidural cavity, the curative effect is rapid and satisfactory, and it can control the pain for a long period of time. The pain relief rate of radiotherapy for common breast cancer, lung cancer, prostate cancer, thyroid cancer and bone metastases of bone marrow cancer can reach more than 80%. Chemotherapy can be considered for multi-site pain that cannot be relieved by local palliative radiotherapy. When the tumor growth is sensitive to chemotherapy, the pain caused by the tumor can generally be relieved by chemotherapy. The growth of cancerous tissues such as advanced breast cancer and prostate cancer is significantly affected by hormones, and the same hormones are also effective for pain caused by cancerous tumors. Exogenous hormone levels must exceed endogenous hormone concentrations and will certainly cause complex changes in endogenous hormone secretion in the body. Neurolysis, percutaneous or open anterior lateral column dissection of the spinal cord and stereotactic central nerve cauterization, which are destructive surgeries, are also effective in controlling some of the cancer pain. 4, Prospect of pain control in palliative medicine The principle of future palliative medicine should be to achieve standardization of understanding globally; deepen the application of the World Health Organization’s three-stage ladder of analgesic therapies, and continually introduce new advances in related disciplines. analgesia with SC salmon and eel-calcitonin, new therapies of opioid combinations and rotations, advances in analgesia with neuropathology, and advances in analgesia with NSAIDs, especially highly selective cyclo-oxygenase 2 ( COX2) inhibitors, and the discovery of the antiemetic and antidepressant effects of substance P receptor antagonists are some of the more recent approaches that may be of value for clinical use. The use of gene transfection to obtain permanent ecological chromophobe tissue spinal cord transplantation for analgesia is expected to solve the problem of difficulty in obtaining autologous chromophobe tissue. Morphine 300 mg orally, 100 mg intravenously, 10 mg in the epidural space, and 1 mg in the subarachnoid space had the same analgesic effect, but the inhibitory effect on mental status and the effect on quality of life were apparently quite different. These differences show good prospects for regional analgesia in future cancer pain control. It is the unremitting pursuit of palliative medicine practitioners to enrich and improve the development of palliative medicine from different perspectives and to realize the goal of pain-free cancer patients worldwide as soon as possible.