About 70% of patients with advanced cancer are suffering from different degrees of cancer pain, most of which are not satisfactorily treated. For this reason, WHO has put forward the ambitious goal of “making cancer patients pain-free”. Therefore, the treatment of cancer pain is one of the important topics in pain research. At present, WHO recommends the first choice of “three-step therapy”, but some cancer pain patients still suffer from severe pain after receiving “three-step therapy”, or some patients cannot receive regular “three-step therapy” due to inability to eat, drug contraindications, drug side effects, and so on. Some patients are unable to receive regular “three-step therapy” due to inability to eat, drug contraindications or drug side effects. Therefore, it is still necessary to seek other treatment methods, such as nerve block, nerve destruction therapy, PCA therapy, transdermal drug delivery therapy, etc. These methods are part of the three-step therapy. These methods are effective supplements to the three-step therapy, which can not only reduce or control pain, but also improve the quality of life of patients and provide opportunities and time for further anti-cancer treatment. “Clinical practice at home and abroad has proved that more than 90% of cancer pain patients can have their pain relieved and quality of life improved if they are treated strictly according to the principle of “three-step therapy”. The first ladder is based on non-steroidal anti-inflammatory and analgesic drugs (NSAIDs), whose mechanism of action is to inhibit cyclo-oxygenase to reduce the synthesis of prostaglandins (PG), which include PGE-1 and PGE-2. PGE-1 has the effect of maintaining the normal function of kidneys and platelets, and protecting gastrointestinal mucous membranes; and PGE-2 has the effect of causing inflammation and pain. Traditional NSAIDs have no selective inhibition of the synthesis of PGE-1 and PGE-2, so while playing an analgesic role, gastrointestinal irritation, renal damage and coagulation dysfunction and other side effects will inevitably occur. Currently developed NSAIDs new drugs, trying to selectively inhibit PGE?2, or by changing the chemical structure of the drug, or the use of controlled-release and slow-release technology, in order to reduce the side effects of NSAIDs, can be selected from more than a dozen of NSAIDs, the WHO recommended representative of the drug for aspirin. The author prefers anti-inflammatory pain among NSAIDs. Anti-inflammatory pain is available in three dosage forms: regular anti-inflammatory pain tablets, anti-inflammatory pain suppositories, and anti-inflammatory pain controlled-release tablets (Istin). The usual dose of 25-50 mg is 25 mg/tablet, taken orally three times a day with meals. For patients who cannot take it orally, anti-inflammatory pain suppositories can be used for rectal administration, which not only reduces gastrointestinal irritation, but also eliminates the first-pass effect. Through the controlled release technology, the anti-inflammatory and analgesic effect can be maintained for 12 h, thus avoiding the side effects caused by too high blood concentration. In addition, painkillers, oxytocin and euthyrox can also be used. Weak opioids are the mainstay of the second phase of the drug regimen, and codeine is the representative drug recommended by the WHO. Codeine is transformed into morphine in the body, which acts on morphine receptors and exerts analgesic effects, with an analgesic efficacy of 1/12 of that of morphine, a duration similar to that of morphine, a weaker sense of euphoria and addiction than that of morphine, and a slight inhibition of the respiratory center, with no obvious constipation, urinary retention, postural hypotension and other side effects. Lugaike is a compound preparation of dihydrocortisone 10 mg and acetaminophen 500 mg, which can exert analgesic effects through different pathways. The oral dose is 1~2 tablets/dose every 6 h. Chimandine is an extended-release tablet of tramadol hydrochloride, which enhances analgesic effect by agonizing different receptors (opioid receptors and alpha receptors) in the center. Starting with 50 mg orally, the dosage should be increased gradually, generally not more than 400 mg/d, and the interval between doses should not be less than 8 h. Shuangkeling is codeine controlled-release tablets, the analgesic effect of which is twice as much as that of codeine, and the interval between doses can be prolonged, without interfering with sleep, and it can be taken once every 12 h, each time with 60-120 mg. The above medicines can be selected according to the patient’s degree of pain and drug-resistance situation. The third step of medication is based on strong opioids, and the representative drug recommended by WHO is morphine. Morphine acts on central opioid receptors and has strong analgesic, sedative and cough suppressant effects. Because of the poor selectivity of opioid receptors, it can inhibit the respiratory center, narrow the pupil, dilate the resistance and volume blood vessels (causing postural hypotension), stimulate the intestinal smooth muscle and sphincter (causing constipation), constrict the ureter and increase the bladder sphincter tension (causing urinary retention) and other side effects, and repeated application can lead to tolerance, addiction and other side effects. Oral morphine is available in two dosage forms. The immediate-release type has been abandoned because of its short duration of action, cumbersome administration, unstable blood concentration and easy addiction. Controlled-release type can make morphine release slowly, reduce the number of times of administration, maintain a more stable blood concentration, and fewer side effects. Mescaline (morphine hydrochloride controlled-release tablets) is commonly used in the clinic and is administered once every 12 hours. The third ladder of medication should especially follow the principle of on-time administration and individualized dosage, remove the traditional concept of morphine medication (fear of addiction, emphasis on respiratory depression), mainly according to the patient’s degree of tolerance, in order to completely relieve the pain of medication. The “on-time administration” can maintain a stable blood concentration, which can effectively relieve pain and avoid the production of euphoria, and is not easy to become addicted, which must be clearly explained to the patient and his family. This point must be clearly explained to the patients and their families. “Administering drugs when in pain” is a major taboo in cancer pain treatment. The clinical dosage of morphine is highly variable and is related to the existence of individual differences in sensitivity to opioid receptors, and clinical administration should follow the principle of dose individualization. The dose of mesocontin can sometimes be as high as 1200 mg/d; mesocontin 10 mg/d has been reported to last for months or even years. Therefore, the use of morphine preparations should be rationalized under the correct assessment of the patient’s pain level to completely relieve the patient’s pain. Adjuvant medication should always be used throughout the treatment of the “three-step program”, and the authors believe that adjuvant medication is the key to the successful implementation of the “three-step program”. The purpose of auxiliary drugs and drugs have two categories: ① enhance the analgesic effect of opioid drugs, relieve the pain brought about by anxiety, depression and irritability and other psychiatric symptoms, including stabilizers such as Valium, triazolam; antidepressants such as amitriptyline; anti-spasmodic drugs such as carbamazepine, phenytoin sodium, etc., the drugs have a mild analgesic effect, the main use of its regulation of the patient’s mental state, to improve the quality of life and to improve sleep; targeted preventive or preventive measures, or to improve the quality of life, the role of the patient’s mental state. (ii) Targeted prevention or alleviation of the side effects of various analgesic drugs, including gastric mucous membrane protective agents, gastrointestinal power drugs and laxatives, etc., which can avoid the premature side effects of analgesic drugs, such as nausea, vomiting, constipation, etc., and the emergence of serious side effects can impede the smooth progress of the “three-steps ladder”, and sometimes it will be forced to interrupt the treatment. Therefore, from the beginning of cancer pain treatment, special attention should be paid to auxiliary drugs, which can be classified as routine drugs, so that patients can smoothly accept and complete the “three-step ladder” treatment. Transdermal therapeutic system (TTS) Long-term and correct oral application of opioids is an effective method of treating cancer pain, and it is also the preferred method recommended by WHO. However, a considerable number of patients are unable to take medication orally due to severe nausea, vomiting and gastrointestinal disorders, so other routes of administration must be used. According to the survey, the application of opioids in patients with advanced cancer pain often requires the use of different (at least two) routes of administration. Transdermal administration is a simple and convenient method of continuous drug delivery. Compared with the oral route of administration, TTS has a long duration of action, avoids the first-pass effect of the liver, has a high degree of bioavailability, has fewer toxic side effects, especially stable blood concentration, and is not likely to cause respiratory depression as well as euphoria or addiction; compared with the parenteral route of administration, TTS is non-invasive, requires no equipment, is less expensive, and is easy to be accepted by the patients when used in the home or in hospitals without the need for supervision by healthcare personnel. Not all drugs can be made into transdermal formulations. The transdermal drug delivery system itself has strict requirements for drugs. Fentanyl’s low molecular weight, high lipid solubility, high efficiency, and non-local irritation physicochemical properties make fentanyl an ideal choice for transdermal patches, and it is currently the only opioid transdermal patch available. Fentanyl transdermal patch (durogesic) has a five-layer structure: backing membrane, drug storage, rate-limiting membrane, adhesive layer and protective layer. The protective layer is removed and the adhesive layer is applied to the skin surface, allowing the drug to pass freely; the rate-limiting membrane determines the rate of fentanyl penetration into the skin; the drug memory stores fentanyl for 72 h of sustained release; and the dorsal membrane is mainly used to prevent the ineffective release of fentanyl. The amount of fentanyl released is directly proportional to the surface area of the TTS. Dorigi is available in 4 sizes, i.e., 10, 20, 30, and 40 cm?2, and can provide 4 different release rates of 25, 50, 75, and 100 μg/h, respectively. 12-24 h after the first application of 100 μg, serum fentanyl concentration reaches a relative steady state, and is maintained at the peak serum concentration from 24 to 72 h, which ensures the basic requirement of analgesia. Replacement of the patch once in 72 h can keep the blood concentration relatively constant. Fentanyl transdermal patch can provide a simple and effective method for patients with advanced cancer pain who need to be treated with analgesic drugs by extraintestinal route for a long period of time, avoiding frequent use of drugs and ensuring sleep, especially suitable for patients with nausea, vomiting or inability to swallow. However, it also has certain shortcomings, slow onset of action, often need to add other analgesics before reaching the steady state blood concentration, lack of dosage regulation, after stopping the administration of fentanyl, the elimination half-life of fentanyl is longer; therefore, if the drug is discontinued because of the side effects, the time of supervision and management should be prolonged, especially for the elderly, frail and malignant patients should be especially careful. Since fentanyl is metabolized by the liver and kidneys, it should be used with caution in patients with hepatic and renal insufficiency. In conclusion, Dorigi is a non-invasive, easy-to-use, long-acting analgesic drug, which is most suitable for patients with persistent pain with a single cause of pain and small fluctuations in pain level.