I. Overview.
Pain is an unpleasant sensation and emotional feeling accompanied by substantial or underlying tissue damage. Pain is a common symptom of cancer. 25% of patients have pain at the time of cancer diagnosis, and about 75% of patients with advanced disease have pain. Pain can cause discomfort to patients and affect their activities, mood and quality of life. Good pain control can not only improve patients’ quality of life, but also improve treatment compliance.
In 1982, WHO proposed the goal of making cancer patients pain-free worldwide by the year 2000. In response to the WHO’s call, the Ministry of Health of China promulgated a notice on “three-stage pain relief treatment for cancer patients” in April 1991 and 1993 respectively.
Classification of cancer pain
1. Somatic pain: the location is generally clear, and it can be acute pain or chronic pain. For example, tumor bone metastasis and postoperative wound pain. Stimuli include various mechanical, chemical or temperature, and also include chemicals such as acetylcholine, bradykinin, histamine, prostaglandin, 5-HT, etc., released after tissue damage caused by various reasons.
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3.Neuropathic pain: caused by dysfunction or injury of peripheral nervous system or central nervous system. Tumor infiltration, compression of peripheral nerves or spinal cord, as well as nerve damage caused by surgery, radiotherapy and chemotherapy can lead to neuropathic pain. Its characteristics are: burning-like, electric shock-like pain, sometimes with a bundle-like sensation, and some patients are accompanied by neurological dysfunction.
Causes of pain caused by lung cancer.
1.Metastasis or direct infiltration of lung cancer: most commonly bone metastasis, compression or infiltration of nerves or internal organs. Pain is often the first manifestation of bone metastasis. The incidence, location and degree of pain are related to the cytological type, location and different stages of lung cancer. (80%-90%)
2.Pain caused by diagnosis and treatment: (10%～20%)
(1) Pain from puncture, biopsy and surgical incision, including chronic incisional pain.
(2) chemotherapy: drug extravasation or irritation of blood vessels, gastrointestinal reactions, myalgia, arthralgia, mucositis, etc.
(3) Radiotherapy: skin burns, bone and joint damage or necrosis, secondary pneumonia.
(3) Comorbidity not related to cancer: other benign pain, such as osteophytes, herniated disc, migraine, osteoarthralgia, etc. (<10%)
IV. Pain relief methods for lung cancer pain and their selection.
(a) Pain relief methods.
1.Anti-cancer treatment to eliminate the root cause of pain (cure): surgery, radiotherapy or chemotherapy, etc.
2.Treating pain to change the pain perception (treating the symptoms): applying various analgesics or other analgesic methods to improve the pain threshold of CNS or block the pain transmission pathway to achieve the purpose of analgesia.
(2) The following points should be noted when choosing pain relief methods.
1.Find out the causes of lung cancer pain and provide targeted treatment.
(2) Choose pain relief methods that are less invasive, have fewer side effects, have good pain relief effects and can restore patients’ daily life and organ functions to the greatest extent.
3.Individualized pain relief should be implemented, and the pain relief plan should be adjusted according to the changes of the disease at any time.
4.Comprehensive treatment: including elaborate care, psychological comfort and recreational activities to distract patients’ attention from pain and reduce pain.
V. Three-step pain relief method for lung cancer pain.
(a) Principles of drug treatment for lung cancer pain.
1.Change the concept and raise awareness: pain torments patients for a long time, with loss of appetite, malnutrition, lowered immunity, disturbing and affecting sleep, and loss of confidence in chemotherapy and radiotherapy.
2.Timely dosing: dose at intervals according to the effective action time of the drug, generally 4-6 hours to take the drug once. Only when the drug is given regularly to maintain a certain blood concentration, can the patient get continuous pain relief.
3, relaxed restrictions: as long as the drugs are used in strict accordance with the WHO and China’s three-step pain relief program, it is not common for opioid addicts.
4.Oral administration: easy and simple, avoiding traumatic, conducive to patients’ long-term medication, rectal or skin administration for those who cannot take orally, and then intramuscular or intravenous administration.
5.Step pain relief: described below.
6.Individualized medication: choose the appropriate dose (good pain relief and minimal toxic side effects).
Give non-opioid, weak opioid and strong opioid analgesic drugs according to the degree of pain (mild, moderate and severe), and correctly and appropriately cooperate with the choice of auxiliary drugs (Valium, Scholastin, Carbamazepine, Chlorpromazine, Fenadrine, hormones, etc.).
1. The first step: for mild to moderate pain, non-opioid analgesics are preferred. Represented by aspirin (non-steroidal anti-inflammatory analgesics and antipyretic analgesics, NSAID). There is a capping effect.
Aspirin 0,3 to 0,9/Q4-6h; diclofenac sodium (Devine) 25-50mg/Q4-6h; paracetamol 0,5 to 1,0/Q4-6h; acetaminophen 500-1000mg/4-6h (compound cloxazolazone-lunanbest component; tylenol, etc.); ibuprofen 200-400mg/Q4- 6h; anti-inflammatory pain 25-50mg/Q4-6h, etc.
Other COX-2 selective inhibitors (celecoxib, celecoxib, etc.).
2. Second order: moderate pain (pain is obvious and unbearable, sleep is disturbed, and the patient requires analgesics), ineffective for non-opioid drugs. Weak opioids are chosen and can be combined with non-opioids to increase the efficacy. Prefer codeine.
Codeine: 30-60mg/Q4-6h;
Tramadol: 50-100mg/Q4-6h PO; 100-200mg/Q6-8h IM.
Others such as the combination of codeine and paracetamol (aminoglutethimide 1 and 2).
3. Third order: severe pain (pain is severe and unbearable, sleep is severely disturbed, there may be passive body position or autonomic dysfunction performance (such as sweating, increased heart rate, pallor, decreased blood pressure, etc.). Ineffective with weak opioids, strong opioids are chosen and may be combined with weak opioids to increase efficacy. No capping effect. Morphine is the representative drug.
Morphine: 5-30mg PO Q4-6h for the first time; later, 10-30mg IH or IM Q4-6h each time; morphine controlled-release tablets 10-30mg Q12h.
Methadone: 10-20mg/dose (t1/2=7, 5 to 48 h).
Dulcolax:for acute pain relief only, generally not used for chronic pain in lung cancer (because it will produce tremors, convulsions, muscle spasms, grand mal seizures when it reaches a certain concentration). 50-100 mg PO or IM Q3-6h.
Fentanyl: transdermal patch (Doregis). Absorbed through the skin, especially for those who cannot take it orally. The rate of drug absorption is related to the area of the patch. Usually changed once in 72 hours to maintain efficacy.
The above three steps of drug delivery can be accompanied by the use of adjuvant drugs for the treatment of specific types of pain or other pain-related symptoms to increase the analgesic effect of opioids.
(iii) Side effects of opioids.
1, constipation: will not be tolerated with the prolonged use of drugs, so the beginning of use should pay attention to prevent the occurrence of constipation. Can use laxatives or laxatives (full course).
2, nausea and vomiting: antiemetic drugs should be given prophylactically. Such as gastric renformation or morpholine 10-20mg PO Q6h.
3, sedation: generally tolerated quickly, if it lasts more than a week, should be checked for other causes of sedation: CNS lesions, combined with other sedative drugs, hypercalcemia, etc.
4. Respiratory depression: caused by opioid overdose. Morphine is the most common. Can be rescued by naloxone.
5, drug resistance and dependence: attention should be paid to the distinction between drug resistance, physical dependence, psychological dependence 3 different concepts.
(1) Drug resistance: With the repeated use of drugs, the efficacy decreases, and it is necessary to increase the amount of drugs or increase the number of doses to maintain the effect of pain relief. This is related to morphine receptor desensitization.
(2) Physiological dependence: When the drug is suddenly stopped or reduced too quickly, the so-called “intermittent syndrome” occurs, which is a pharmacological phenomenon.
(3) Psychological dependence: the so-called addiction, which is mental dependence. It is the patient’s desire to use the drug, unstoppable attempts to obtain the drug, for “comfort” rather than for pain relief. The incidence is only 1/3000.
Take morphine consumption per capita as an example, although the medical consumption of morphine in China has increased more than 30 times (the per capita dosage rose to 0,195 mg/year in 2002), it is still far from the level of economically developed countries (>10 mg/year) and medium developed countries (1 mg/year).
Other pain relief methods for lung cancer pain.
(a) Radiotherapy.
1.Bone metastasis of lung cancer: palliative radiotherapy.
2. Chest wall pain: palliative radiotherapy.
3.Mediastinal pain: short course radiotherapy.
4.Supraspinal sulcus tumor: fractionated radiotherapy.
(B) Chemotherapy: only for those who are sensitive to chemotherapy.
(c) Nerve block anesthesia treatment: local anesthetic or nerve-destroying drug is injected into the ganglion, nerve trunk or plexus and its surroundings to block nerve conduction. This method is suitable for those with severe and limited pain and clear diagnosis.
(iv) Psychotherapy: The purpose is to reduce the despair and fear of lung cancer patients and enhance the confidence of treatment.
(v) Other treatments: osteolysis inhibitors (phosphonates such as bone phosphonate, Yunque, etc.).