Author: Kara Bucci, MD and and Joel W. Goldwein, MD
Abramson Cancer Center of the University of Pennsylvania
Last Modified: April 20, 2004
For many people, the scariest part of a cancer is the threat of pain. People living with cancer need to know that pain is not something they will definitely experienceÃ‘and if they do, it often can be well-controlled through medication, radiation, anesthetic or neurosurgical techniques, or cognitive-behavioral approaches. It is important to emphasize that pain is treatable. Significant advances in pain control have been made over the last decade. Many studies have shown that the fear of pain, including the fear that it will worsen, can make people perceive it as more severe. But when people know that they have options for treating their pain, they often begin to perceive it as less severe.
Cancer can cause pain in several different ways. Pain can result from something called "mass effect," which means that the tumor is physically pressing on an organ or body part. The simplest way to treat this kind of pain is by surgically removing as much of the tumor as possible (or "debulking" it). However, not all cancer patients are good candidates for debulking surgery. Other treatments such as radiation and/or chemotherapy may achieve the same effect as debulking.
Cancer can also cause "bony" pain, which occurs when tiny cancer cells get inside bones and damage their structure. Frequently, irradiating the bone treats this type of pain. The radiation therapy destroys most of the tumor cells, allowing the bone to start healing.
Pain can also occur when cancer grows directly into a nerve, making the person feel like pain is coming from any place that nerve goes. This is an example of "referred pain," the term used to describe pain felt at a place different from that where the injury is occurring. Sometimes a nerve block, or the process of making the whole nerve numb, can be used to treat this type of pain. Again, all of these types of pain may be treatable with combinations of surgery, radiation, and chemotherapy to reduce the tumor itself.
Some of the pain experienced by cancer patients isn't from the cancer at all, but from the treatment. Certain types of chemotherapy can cause "neuropathy" (from "neuro," relating to nerves, and "pathy" meaning bad or sick, so literally "sick nerves"). Examples of neuropathy include numbness, tingling, or pain, usually in the feet and lower legs or the hands. Radiation therapy can cause some damage to healthy tissue, which may also be painful. Sometimes healthy tissue gets "fibrosed" or hard from radiation, and doesn't feel normal. If part of the intestine gets radiation, the person may experience painful cramping and diarrhea. Occasionally the intestine can get obstructed, or blocked, by scar tissue from radiation or from surgery, or it may even be blocked by the tumor itself. Many opioids or narcotics that are used to treat pain can cause severe constipation, which may be painful. People taking narcotic pain medicine may also need to take a stool softener. Surgery, which may be used to remove a tumor, may itself cause pain either directly from cutting and injuring tissues, or indirectly by causing scar tissue formation.
The prevalence and severity of pain are difficult to assess for a number of reasons. First, pain is subjective. There is no objective test or study that can measure how much pain a person is experiencing. Physicians simply have to accept that patients are in as much pain as they say they are. Second, some people tend to underreport their pain. When they're at their doctor's office, their attention is focused on the extent of their disease, recent study results, and new treatment plansÃ‘and many people simply don't mention whether or not they are in pain if not asked directly. Furthermore, many people downplay the extent of their pain because they don't want to be seen as a "wimp" or "complainer." Third, different people describe things differently. Of two people in an equal amount of pain, one might describe it as "occasional" and "bearable" and the other as "frequent" and "severe." Or the same person might describe his or her pain differently on two different days. There are cultural difference in how pain is tolerated, and pain can be exacerbated by anxiety and other indirect factors.
Clinical studies of pain suggest that about one-third of patients currently receiving cancer treatment experience moderate to severe pain, and 60 to 90% of people with advanced disease report a similar amount. However, a recent study from the World Health Organization reports that 70 to 90% of all cancer pain can be controlled. Patients need to communicate the intensity and amount of pain to their physicians adequately, and physicians need to be vigilant about trying to treat pain.
Several different factors are used to assess pain, including:
All of these factors are important when trying to decide upon the best strategy for treating pain.
Physicians frequently refer to a "pain ladder" when planning treatment. The first step in pain management is the use of analgesics, or pain medications. For mild pain, an over-the-counter medicine such as aspirin, TylenolÂ¨ (acetaminophen), or MotrinÂ¨ (ibuprofen) may be sufficient. Some of these drugs are classified as NSAIDs (Non-Steroidal Anti-Inflammatory Drugs). If these are not sufficient, physicians move on to the next "step" on the ladder: a stronger medication, such as an opioid (or narcotic) in addition to an NSAID. Opioids include medications such as codeine and morphine. Many opioid medications, like PercocetÂ¨ and VicodinÂ¨, are already mixed with an NSAID. If these are still not strong enough to take care of the pain, physicians move to the third step in the ladder, a higher dose of an opioid. Most of these medications are available in all forms including pills, liquids, suppositories, shots, and even skin patches that can be worn for several days.
Most physicians and pain specialists feel that the best way to treat chronic pain (pain that lasts for more than a few days or weeks) is to "keep ahead of it" with medication. This means taking enough medication so that it doesn't wear off before the next dose. If the medication does wear off, "breakthrough" pain occurs. People usually need less medication to prevent breakthrough pain than to get rid of it once it occurs, so doctors recommend preventing it.
There are other groups of medicines besides NSAIDs and opioids that can be used to treat pain. These include medications that are primarily used to treat other disorders. Examples are some seizure medications, certain anti-depressants, corticosteroids (anti-inflammatory drugs), and some blood-pressure medications. They are usually used in combination with an NSAID or an opioid.
Narcotics very rarely cause addiction in this setting. Addiction has repeatedly been shown not to be as much of an issue as many patients and physicians fear. In fact, pain commonly is undertreated due to the false belief that the patient may become addicted. Addiction is the loss of control associated with taking a drug. Behaviors that imply addiction include stealing drugs or money for drugs, lying to get them, and using drugs that are harmful to oneself. These are not the behaviors that cancer patients typically exhibit with regard to the medication necessary for their comfort. It is also important to make a distinction between addiction and tolerance. People taking medication may develop tolerance, meaning that they may need more of the medication to get the same effect. Provided that they are not engaging in dishonest behaviors to obtain the medication, and they are not harming themselves with it, this is not addiction.
Unfortunately, there are side effects associated with pain management. Pain medication may cause side effects such as nausea, sedation and drowsiness, and constipation. Most patients develop tolerance to the sedative effects of narcotics; that is, the dose needed to control pain may cause sedation at first, but this side effect eventually subsidesÃ‘even though the same dose will continue to control pain. If the medication causes constipation, however, this effect does not usually wear off, and many people need to take a stool softener or laxative. A patient experiencing severe nausea may need to switch medications; the fact that one medicine causes nausea does not necessarily mean that another similar medicine will.
A technique called Transcutaneous Electrical Nerve Stimulation (TENS) has been shown to be effective in the treatment of certain types of pain. TENS involves giving small, non-painful electrical bursts to strategically located areas in the skin. This is considered a safe, non-invasive approach to treating pain, but it may not be effective for all patients.
Anesthesiologists are capable of injecting a numbing medication directly into the nerve that goes to the area that is painful. The patient will experience numbness and may have trouble moving the part of the body that's been treated. In severe cases of unremitting pain, neurosurgeons can cut the nerve that goes to the affected area. This treatment is more likely to be considered in an area that has already lost function.
Acupuncture is the stimulation of selected points in the body, usually with a small needle that is manipulated by the acupuncturist. In Asia, it has long been viewed as a reliable method for treating both a disease and its symptoms. There is no evidence that acupuncture can cure any known disease, and Western physicians are reluctant to use acupuncture for treatment. However, there are many reports of acupuncture's usefulness in treating pain. In one study of acupuncture in cancer patients experiencing pain, slightly over half of those treated reported that their pain improved.