Controlling cancer pain is a key component of any overall treatment plan; the most successful methods combine multiple therapies to prevent pain. When pain does break through, the proper dose of pain reliever should be taken immediately. Many patients have a tendency to wait until the pain is excruciating before seeking relief, but waiting too long often requires the use of more painkillers and produces less effective pain control.
Estimates of the incidence of persistent pain among cancer patients range from about 14 percent to almost 100 percent. The most common estimates found that pain was poorly controlled in 26 to 41 percent of all cancer patients. One obstacle to measuring the scope of the problem is that patients themselves often give their doctors poor insight into their pain; some believe that pain is part of the cancer experience and must be tolerated. Other patients have an unrealistic fear of opiates and often choose to suffer instead of requesting painkillers.
The best pain treatment depends on the level of pain and its cause. Mild pain often can be treated with acetaminophen, aspirin, or a nonsteroidal anti-inflammatory drug (NSAID). Ibuprofen and naproxen are two NSAID s frequently used for mild cancer pain. Moderate to severe pain usually requires an opioid, usually beginning with codeine and progressing to other options, such as oxycodone, morphine, and hydromorphone.
Long-acting narcotics such as methadone and sustained-release morphine sulfate are used when breakthrough pain is a problem. For patients who have swallowing problems, options include liquid morphine and a fentanyl skin patch.
Although pain is not always a prominent feature of cancer, it is one of the most feared symptoms. Today there is no reason why most patients with cancer pain cannot be made comfortable.
The first step in managing cancer pain is proper evaluation. There are various types of pain in cancer, whether it is caused by injury of tissues around the tumor (nociceptive pain), the tumor’s stimulation of nerves (neuropathic pain), or individual mental responses to sensation from the tumor (psychogenic pain). Not surprisingly, patient self-reports are the most useful way to assess pain. A full history, physical exam, and appropriate lab and imaging studies (X-ray, computed tomography [CT], magnetic resonance imaging [MRI]) should reveal how the disease process is producing pain. But the pain’s intensity, features, and factors that influence it are all important in helping patients decide the best strategy for treatment.
Certain procedures involved in cancer diagnosis or treatment can sometimes produce acute pain; these include bone marrow biopsy, chemotherapy (especially by injection), immunotherapy (pain in the joints or muscles), and radiation therapy (inflammation of the mucous membranes). Such pain can usually be managed with adequate dosages of nonmorphine painkillers.
The most common chronic cancer pain is caused by bone pain. Experts do not know why some bone metastases are painless and others are painful. If the spine is involved, there may be damage to the spinal cord or nerve roots. Chemotherapy can sometimes cause persistent nerve pain, which stops when the drug is discontinued.
The most typical method of easing pain in cancer patients involves the relatives of morphine called opioid derivatives. The choice of drug depends on the patient’s age, the presence of liver or kidney disease, and possible interactions with other medications. Although taking drugs orally is usually preferred, other methods (such as the transdermal skin patch) can be used if the patient has trouble swallowing or experiences any severe gastrointestinal upset.
For continuous or frequently recurring pain, it is usually best to follow a fixed dosage schedule (such as every four hours) rather than giving the drug “as needed.” Starting at a low dose, the dosage is increased until pain stops or side effects prevent an increase. If pain breaks through the schedule, a rescue dose can be added immediately; rescue dose levels are typically 5 to 15 percent of the total daily dosage of the drug.
Oral doses can be given more often, if necessary, with as little as two hours between doses; the minimal interval between intravenous (IV) administrations can be as short as 10 to 15 minutes. It is important that everyone know that there is no correct or maximum dosage for cancer patients, short of overdose — the correct dosage is whatever prevents pain. Addiction should not be a concern for patients with cancer.
In many cases, the development of side effects does not prevent further increase in dosages; the treating physician can prescribe medications or other therapies to counteract the most common problems seen with opioids, such as nausea, vomiting, and constipation.
Acetaminophen and nonsteroidal anti-inflammatory drugs (NSAIDs) are good painkillers, but they have a maximum dose level above which no more benefit can be expected. These medications are most useful for people who have bone pain or inflammatory pain in which the affected area is warm, red, and swollen. The newer cyclooxygenase-2 (COX-2) inhibitors may be superior types of NSAIDs in preventing stomach or kidney toxicity. In addition, certain types of cancer may do well with a particular drug directed at the tissue involved, such as treating bone pain with bisphosphonates (Fosamax) or calcitonin.
Adjuvant medications are drugs that help analgesics work more effectively. Some drugs that are not primarily painkillers may have pain-relieving activity as well as their main effect. For instance, steroids, antidepressants, some anesthetics, antiepilepsy drugs, and major tranquilizers may be helpful in various cases of nerve pain. They are usually given after opioid therapy has been stabilized. Adjuvant drugs include the following:
- • Tricyclic antidepressants such as amitriptyline and doxepin can improve the action of opioids.
- • Benzodiazepines such as lorazepam and diazepam control anxiety to help reduce dosage of pain pills.
- • Selective serotonin reuptake inhibitors (SSRIs) and other antidepressants improve mood.
- • Nerve-pain modulators such as gabapentin control pain through a mechanism that does not affect opioid brain receptors.
Radiation Therapy and Chemotherapy
In addition to its main use as a way of destroying cancer cells, radiation therapy is often used to control pain, chiefly in managing the spread of cancer to the bone from the prostate. Chemotherapy can provide pain relief in prostate cancer due to tumor shrinkage; however, this improvement should be balanced with the toxic effects that chemotherapy can produce.
There are many alternative treatments for cancer patients whose pain is not adequately controlled by medication, primarily provided by specialists in hospital settings. A cancer treatment center or pain clinic is the best place to obtain information and advice about these therapeutic approaches, if the patient’s cancer management team does not offer them. The following are most common:
- • Acupuncture
- • Exercise
- • Heat or cold treatment
- • Massage
- • Breathing exercises
- • Relaxation techniques
- • Hypnosis
- • Individual, group, or family psychological therapy