Cancer Pain Treatments
There are many ways to relieve cancer pain, from drugs to surgery to acupuncture. Treatments vary from individual to individual, depending on the type and severity of pain, risk factors involved with using a particular treatment, and personal preference. Opioids, a common treatment for pain, can lead to dependence, addiction and tolerance. For several reasons, cancer pain is often undertreated. Some of the most common treatments are:
- Analgesic drug therapy
- Non-opioid analgesics
- Opioid analgesics
- Adjuvant drugs
- WHO three-step analgesic ladder
- Anesthetic and neurosurgical pain management
- Neurostimulatory procedures
- Diathermy and cryotherapy
- Therapeutic exercise and massage
- Behavioral methods of pain control
Analgesic Drug Therapy
Medicines that are used to relieve pain are called analgesics. Analgesic drug therapy is the main pain relief method used for most cancer patients. 70–90% of a cancer patient's pain can be controlled using a combination of nonopioid, opioid, and adjuvant drugs, usually following the simple rules of the WHO three-step analgesic ladder. Analgesics do not cure the cause of the pain and provide only temporary relief. But they make short-term pain tolerable.
For mild pain, people can buy over-the-counter, nonprescriptive analgesics, such as aspirin, acetaminophen (e.g., Tylenol®), or ibuprofen (e.g., Advil®). Aspirin and ibuprofen are two of many non-steroidal anti-inflammatory drugs (NSAIDs). There is an upper limit to how effective they are (increasing the dose above a certain maximum point no longer continues to provide greater relief), and they are non habit-forming. Due to potentially severe gastrointestinal and cardiovascular side effects, NSAIDs should only be used as instructed.
Stronger analgesics can be prescribed by a physician. Studies indicate that 20-40% of patients who seek pain relief are satisfied with nonopioid analgesics alone. Patients vary in how they respond to the different nonopioid analgesics, and finding one that works may require trial and error.
Morphine is the prototype opioid analgesic, though opioids vary in effectiveness and side effects. Unlike nonopioid analgesics, most opioids do not have an upper limit of effectiveness. Pain relief increases as the dose increases, to the point of causing unconsciousness. Opioids are used for severe pain, and the fact that they can be addictive may affect a physician's willingness to prescribe them.
Duragesic® (fentanyl transdermal system) delivers the opioid analgesic fentanyl through a patch that is worn on the skin. It is used to treat moderate-to-severe chronic pain that does not respond to other medications (e.g., nonopioid analgesics, opioid-acetaminophen combinations) and provides continuous pain relief for 72 hours.
Various doses of the fentanyl transdermal system are available and the dose should be individualized to each patient and evaluated at regular intervals. Duragesic is not used to treat postoperative or acute pain and is not prescribed for children under the age of 2. It can be used in patients under the age of 18 who are opioid-tolerant.
Duragesic may cause a life-threatening reduction in breathing rate and depth of breathing (hypoventilation). Repeated administration may result in tolerance and physical and psychological dependence. Other side effects include the following:
- Dry mouth
- Excessive sleepiness (somnolence)
- Excessive sweating
- High blood pressure (hypertension) or low blood pressure (hypotension)
- Nausea and vomiting
Supplemental opioids may be used to treat breakthrough pain in opioid-tolerant cancer patients. The goals of these medications are rapid relief of pain, short duration of effect, and tolerable side effects.
Supplemental opioids (also called "rescue medicines") can be administered in pill or capsule form (oral administration), as lozenges that dissolve under the tongue (sublingual administration) or are absorbed through the inner lining of the cheeks and mouth (oral transmucosal administration), and as rectal suppositories.
Oral opioids usually are the most convenient and the least expensive; however, this method of administration results in a slower onset of action. These medications also remain in the bloodstream longer than necessary, often causing intolerable side effects such as dizziness, sedation, and vomiting.
Although hydromorphone HCl (Palladone™ Capsules) has been approved by the Food and Drug Administration (FDA) to treat opioid-tolerant patients who require extended treatment for persistent, moderate to severe pain, in July 2005, this drug was removed from the market pending further discussions between the manufacturer and the FDA due to potentially fatal reactions that may occur in patients who drink even a small amount of alcohol while taking it. Patients who are taking Palladone™ should consult their doctor for additional information.
Palladone™ is a capsule that is taken once daily and must be swallowed whole and not broken, chewed, crushed, dissolved, or opened. It is available in doses ranging from 12 to 32 mg. Hydromorphone HCl is contraindicated in patients with severe bronchial asthma, paralytic ileus (i.e., intestinal paralysis that prevents digestion and causes intestinal blockage), and known hypersensitivity to the medication.
Side effects include constipation, headache, infection, nausea, and excessive sleepiness (somnolence). Severe reactions include respiratory and circulatory depression, disrupted breathing (e.g., apnea, respiratory arrest), low blood pressure (hypotension), shock, and cardiac arrest.
Studies have shown that sublingual administration (i.e., under the tongue) of morphine may delay the body's absorption of the drug. This method generally is considered to be no more effective than oral administration.
Oral transmucosal fentanyl citrate (Actiq®) can be used to treat breakthrough pain in opioid-tolerant cancer patients. This medication is available in six dosage strengths (200–1600 mcg) and is administered via a lozenge attached to a plastic handle, which dissolves over 15 minutes as the patient moves it along the inside of the cheeks.
Patients should not exceed four doses of Actiq in a 24-hour period. The medication is individually formulated from a starting dose of 200 mcg to a single dosage unit that provides adequate pain relief and minimizes side effects. Patients should be closely monitored and evaluated at regular intervals.
The amount of fentanyl contained in Actiq lozenges can be fatal in children; the medication and packaging should be handled carefully and disposed of properly. Actiq may cause life-threatening hypoventilation in patients who are not opioid-tolerant and should not be used to treat pain in these patients.
Actiq may cause temporary cessation of breathing (apnea), excessive sleepiness, low blood pressure, and a sudden decrease in blood flow (shock). Other side effects include dizziness, nausea, constipation, and muscle weakness (asthenia).
Rectal suppositories provide rapid onset of action, but many patients find this method of administration inconvenient.
Adjuvant drugs are used to enhance opioid analgesics and to provide pain relief for certain types of pain such as neuropathic pain and bone pain. Neuropathic pain is less responsive than other types of pain to both nonopioid and opioid analgesics. Adjuvant drugs are also used to relieve side effects of other pain relievers.
For neuropathic pain, analgesics are always the first course of action, but generally neuropathic pain does not respond well to analgesic drug therapy. Adjuvant drugs used to relieve neuropathic pain include antidepressants, anticonvulsants, oral local anesthetics, cutaneous local anesthetics, corticosteroids, and various others. Antidepressants should be the first course of adjuvant drug therapy. The doses used are far less than what are required to produce a mood-altering effect.
WHO Three-Step Analgesic Ladder
The World Health Organization (WHO) has developed a standardized cancer pain treatment plan that is recognized and used worldwide. Studies show that 70–90% of a cancer patient's pain can be effectively treated using this system. It is based on the idea that analgesic (pain reliever) drug therapy provides the most effective pain relief for cancer patients. The three different steps refer to different combinations of analgesics. The idea is that all patients should start at the lowest rung of the ladder, Step I. If their pain is alleviated at that stage, then there is no need to go any further. If their pain is not relieved, then they should move on to step II and then step III.
- Step I For patients with mild to moderate pain, the use of non-opioids is the treatment of choice. These may or may not be combined with adjuvant drugs (drugs that are used to hasten or add to the primary mode of treatment).
- Step II For patients with moderate pain, who did not feel relief after using only non-opioids, a combination of opioids and non-opioids should be tried. Again, adjuvants may or may not be used.
- Step III For moderate to severe pain, opioids should be used, with or without non-opioids, and with or without adjuvants.
A complex array of psychological and emotional variables play a role in the suffering that a patient with cancer pain experiences. The level of emotional distress that a cancer pain patient feels varies individually, depending on many factors such as personality and family support. It is estimated that 25% of all cancer patients show signs of clinical depression, with the percentage increasing to greater than 70% for patients with advanced stages of the disease. Untreated pain leads to many cancer suicides. Psychotherapy is an important part of cancer pain management. The goals of psychotherapy are to provide emotional support and stability, and to help patients adapt to their crisis situation.
Anesthetic and Neurosurgical Pain Management
These kind of approaches are used in about 10–20% of all cancer pain patients, usually in combination with drug therapy. They work best for well-defined, localized pains (somatic and visceral pain, not neuropathic pain) and are often used only for patients near end-stage illness. Many patients are frightened by the potential damage to the nervous system that these kinds of treatments can cause.
Anesthetics are substances that block nerves so that they can no longer transmit pain signals. Examples of common anaesthetics include nitrous oxide (inhaled through a face mask) and intravenous barbiturates (reserved mainly for dying patients who are suffering extreme pain). There are many others.
The neurosurgical control of pain is the use of surgery to remove the tumor in the nervous system that is causing the pain (antitumor neurosurgery) or block pain pathways (antinociceptive neurosurgery). Antitumor therapy focuses on the cancer, not just the pain, and so it provides cancer patients with the hope for prolonged life as well as relief from pain. The most common antinociceptive procedure used to relieve cancer pain is the cordotomy, which involves cutting bundles of nerves in the spinal cord to interrupt the pain pathway. It is used for patients with short life expectancies who feel somatic pain on one side of their body below the waste. It is usually effective for 1-3 years. Another common antinociceptive procedure is the rhizotomy, which involves cutting specific nerves that are close to the spinal cord. The rhizotomy is used for patients with chest wall pain due to tumor invasion, and it provides effective relief 50–80% of the time.
TENS (Transcutaneous electric nerve stimulation) is a procedure that involves using mild electric currents to stimulate certain nerve endings that, when stimulated, block pain transmissions. It has proven effective for many different types of pain, including neuropathic pain, and is both safe and noninvasive.