Cancer Pain: The Basics
Please use for reference only.
Christopher Dolinsky, MD
The Abramson Cancer Center of the University of Pennsylvania
Last Modified: November 19, 2004
When patients are diagnosed with cancer, they are often overwhelmed with the amount of information they receive about their diagnosis and treatment options. One of the topics that may not be discussed initially is pain. For many people, the fear of pain from their cancer is the most frightening aspect of their diagnosis. Luckily, by working closely with their doctors and nurses, the vast majority of patients who experience pain from their cancer can have it adequately managed with a combination of medications and other treatment strategies.
What is cancer pain?
Pain comes from a variety of different stimuli to a person's body. Pain is a natural signal that is designed to let you know that there is something wrong with a particular part of your body. Pain is transmitted via nerves. Nerves exist in every different tissue in the human body, and if there is a painful stimulus – the nerves carry a signal from the injured area up through the spinal cord all the way to the brain. One of the more poorly understood areas of pain medicine involves how the brain interprets a signal of pain. It appears that a person's state of mind or emotions can influence how they feel the sensation of pain. Doctors in wartime have noted that soldiers on the battle field can receive major injuries that they barely report as painful in the heat of a battle. However, when the same soldiers are moved from the battle field to a hospital, their injuries are then described as extremely painful. Our situation, attitudes, and emotions can all modulate our experience of pain.
Cancer can cause pain in a variety of different ways. If a tumor grows directly into a structure with nerves, this will lead to a sensation of pain. Cancer can invade bones, organs, or even press on nerves. The best way to reduce this type of pain is to treat the cancer directly, by shrinking it or removing it. Until that happens, though, patients will often need pain medications to help them function with their pain.
If cancer presses on a nerve, this can cause a feeling of pain in the area that the nerve came from. Patients can then experience what is called "referred pain". For instance, if a tumor in someone's pelvis presses on a nerve that is traveling up from their foot, they can experience foot pain even though there isn't any cancer in their foot. Your doctor should be able to figure out the location of your disease and pain with a careful physical examination.
Cancer can sometimes block the path of an organ that needs material to flow through it. If cancer obstructs the path of digested food in the gut, then people can experience pain. If a tumor keeps someone from being able to pass urine out of their bladder, this can cause pain. The best way to manage this pain is to remove the tumor, or sometimes (if it is not possible to remove it), your doctors can open up a pathway by "stenting" it open with various devices. Until the blockage is removed, pain medications can be of use to treat this type of pain too.
Sometimes, the pain that a cancer patient experiences is related to the treatments that their doctors use to fight the cancer. People who have surgery can often have short term pain or nerve injury from the incisions. Radiation therapy to the swallowing tube can cause a type of temporary burn (called esophagitis) that can make it painful to swallow. Certain types of chemotherapy can cause damage to the nerves (called neuropathy) that lead to a painful sensation in the hands and feet. Luckily, many of these types of pain are temporary, and the doctors who are experts in delivering their treatment specialty are also experts in treating the side effects of their treatments. It is very important for patients to be honest and open with their health care team so that any treatment related pain issues can be resolved.
How common is cancer pain?
Pain from cancer occurs at different rates depending on the type of cancer and how advanced it is. About 25%-33% of patients with early cancers experience pain, and that number climbs to 75% for advanced cancers. About 75% of all cancer patients will need treatment with narcotic pain medications (see treatment section below) at some point in their lives.
Studies from the World Health Organization show that about 85% of patients with cancer pain can be adequately treated using oral narcotic pain medications alone. Of the other 15%, almost all of them can be effectively treated with a variety of different options (see treatment section below).
How do we measure cancer pain?
Unlike many other problems in medicine, pain is an entirely subjective problem. This means that there is no exact method doctors can use to measure your pain. The only way that your health care team can get a sense of your pain is from you. You are the expert in your own pain. This means that you are going to have to pay attention to your symptoms, be honest with your doctors, nurses and families, and never be afraid to let people know when you are in pain. Your doctors and nurses are never going to be angry or upset with you if you mention your pain to them. Simply "taking it" without telling your team is not a sign of bravery. Your doctors need to know about your pain, because it can often be a sign that your disease is either improving or progressing. Also, managing your pain effectively gives your body the rest it needs to fight off the cancer.
You can help your team manage your symptoms by keeping a record of your pain. Using a daily pain log book or chart (often available at your doctor's office or on the Internet) can be an extremely useful tool for your doctors. Because everyone experiences their pain differently, a log book or chart can help doctors to treat your pain with the correct combination of medications. Another benefit of a log book is that your doctors can see how you have done over time. You may not experience the same level of pain every day, and if you aren't having any pain issues during a doctor's visit – your doctor may not get an accurate picture of your pain.
Pain can affect patients in a variety of different ways
Acute pain comes on suddenly, and is usually from a well defined injury. Acute pain can be treated and generally lasts for a short period of time. Recovery from an operation is one example of acute pain.
Chronic pain lasts for longer than the healing time of an injury. Most cancer pain can be classified as chronic pain. Chronic pain can be broken up into a few different categories as well:
- Intermittent pain is long term chronic pain that comes and goes. It may occur in waves or patterns, and is generally treated with short acting narcotics.
- Persistent pain lasts 12 hours a day or more every day for more than three months. Persistent pain is usually treated with long acting pain medications that treat the pain all day long.
- Breakthrough paincomes on suddenly above and beyond the medicine you use to treat persistent pain. Breakthrough pain may happen several times a day or be associated with certain activities. Breakthrough pain is usually treated with short acting narcotics.
One of the methods physicians and nurses frequently use to get a sense of a patient's pain severity is to ask patients to rate their pain on a scale of 0 to 10, with 0 being "no pain" and 10 being "the worst pain I've ever felt in my life". This can then be followed, and can also be used to help judge a patient's response to treatment.
In addition to asking about pain, your health care team will want to know where the pain is, how it feels to you (is it stabbing, pressure, burning, etc.), what you can do to make it worse or better, and how it is affecting you daily activities. The more information you can provide about your pain, the more likely your doctor will be able to help you with it.
How is cancer pain treated?
The most effective way to treat cancer pain is to get rid of the cancer. The goal of your oncology team is to do just that, but along the way, most patients are going to need something to help them until that goal is accomplished. Surgery, radiation, and chemotherapy can all be very useful for treating cancer pain. The specifics of how your particular cancer is best treated can be accessed in the Types of Cancer sections of OncoLink.
Your doctors will tailor their recommendations on how to treat your cancer pain depending on where your pain is, how severe it is, how it affects your life, and whether or not it comes and goes or is steady and constant. There are a variety of different types of medications that physicians use to treat pain, and as the pain gets more severe, the pain medications prescribed get stronger.
Most people have experience with over-the-counter pain relievers like Tylenol or Motrin. These drugs are useful for milder pain, but cancer pain is usually too strong to be relieved by drugs like these. Instead, doctors often prescribe a class of medications called narcotics or opioids (oh-pee-oids) – the two terms are interchangeable. Narcotic painkillers work by activating certain receptors in the brain that cause pain relief. Narcotic painkillers are the strongest class of painkillers known to mankind. You can read about specific narcotic pain medications in the OncoLink Rx section of OncoLink.
Different types of opioid pain medications can be used depending on the type of pain you are experiencing. Some narcotics last longer than others, and some narcotics have their pain relieving effects come on quicker than others. For instance, patients who experience intermittent pain can get good pain relief with narcotics that are short acting and come on rapidly. Patients who have chronic persistent pain can benefit from long acting medications that stay in their systems for days, all the while providing constant, steady pain control.
Although many people only think of narcotics medications as pills, there are other, different preparations of narcotic medications that can be of great benefit to many patients. When narcotics are given intravenously (through a vein), they come on very quickly and can be quite intense. Intravenous narcotics are generally reserved for patients in a hospital setting, because their use needs to be closely supervised. Another way to deliver narcotics very quickly is in a lozenge attached to a handle. A narcotic called Actiq (Fentanyl Citrate ) is a lozenge attached to a handle that is rubbed on the inside of your cheek, and this causes the pain relieving medicine to make it into the bloodstream very rapidly. Actiq can be of use for patients who need rapid pain relief of intermittent or breakthrough pain outside of the hospital. There are also pain medication patches that are applied to a patient's skin every three days (like transdermal fentanyl). These deliver long acting, steady doses of pain medication and can therefore be used effectively for chronic pain. Talk to your doctor about the best way to manage your pain, and make sure to be honest about your needs and symptoms.
Although opioid medications are by far the most commonly used class of medications for cancer pain, occasionally there may some utility in prescribing other classes of drugs. Anti-seizure medications, anti-depressants, and steroids can all be used to treat cancer pain. One of the more popular medications for a type of pain called neuropathic pain (related to peripheral nerves) is called neurontin.Neurontin can sometimes be useful in addition to opioids in patients with severe or difficult to treat pain.
Side effects to opiate medications are related to the receptors that these medications activate to cause their pain relief. When someone first begins taking narcotics, they will probably experience many of the side effects. However, as a person gets used to these medications, a lot of the unpleasant side effects will disappear.
Common Side Effects
Nausea or vomiting
This is a very common side effect for people who begin taking opioids for the first time. Eating small frequent meals, sucking hard candy, or chewing gum may help.Nausea is usually very mild and subsides after a few days. If your nausea persists, talk to your doctor about ways to relieve it.
Feeling sleepy, drowsy or lightheaded may accompany the use of opioid painkillers. Some people just don't "feel like themselves" on these medications. Avoid driving or any other potentially dangerous tasks that require your concentration and a clear head until you feel normal again. Avoid alcohol or other sedatives while using these medications unless they are specifically prescribed by your doctor. Most people will begin to feel like themselves after a few days on the medications. If you continue to feel "out of it" after a couple of days, talk to your doctor about adjusting your dosages.
Constipation will happen to just about every patient who takes opioids for any significant length of time. More liquids, regular exercise, or a fiber-containing diet may help. Talk with a healthcare provider about a stool softener or laxative if you haven't already been taking one.
Uncommon Side Effects
Slowed Breathing or Low Blood Pressure
You may experience low blood pressure or slowed breathing while taking any opioid painkillers. This usually only occurs when the dose of medication is too high or it is increased too quickly. This rarely happens to patients who have been taking opioid medications for a long time.
These side effects can also result from an overdose of opioids. If you suspect that you or someone you know has taken an overdose of opioids, call 911 immediately. If you feel extremely tired, lightheaded, dizzy, sweaty, nauseated, or short of breath, you need to see a doctor immediately. Sometimes patients who have taken too many opioid medications will be so sleepy that they can't be awakened or aroused. These side effects are emergency situations. If any of these symptoms occur, you should seek emergency medical attention.
Although it is uncommon, some people are allergic to certain opioid preparations. If after opioids, you experience chest tightness, swelling, wheezing, fever, itching, blue skin color or cough, you need to call 911. These side effects are emergency situations. If any of these symptoms occur, you should seek emergency medical attention.
Tolerance, Dependence and Addiction
Just as a person on long-term opioids stops experiencing some of their negative side effects after a while, they may also stop getting proper pain relief. This phenomenon is called tolerance. As patients develop tolerance, they will need higher doses of their opioids to get adequate levels of pain relief. Tolerance is a completely normal aspect of using opioid painkillers, and is nothing to be concerned about. The point of using these medications is to keep pain well controlled, therefore the exact doses that any patient requires are not important as long as they can be kept comfortable.
As a person remains on opioids for a long time, their bodies will begin to adapt to the medications. This causes tolerance, but it can also cause dependence. Dependence means that the body "gets used to" the opioids. Dependence DOES NOT equal addiction. Dependence is a natural, physical phenomenon that happens to everyone on long-term opioid therapy. The only important thing to know about dependence is that once a patient becomes dependent on opioids, they will feel very sick if they stop them abruptly. Patients who are dependent on opioids and stop them all of the sudden will feel lousy, like they have the flu. This is called withdrawal. The way to combat withdrawal is to take someone off of opioids very slowly, not all at once. It is important to remember that dependence and withdrawal are normal, and happen to everyone who takes opioids for a long period of time.
Many people who are prescribed opioid pain relievers are worried that they may become addicted to these medications. This fear stems from the fact that opioid medications can cause euphoria and pleasure when used by people who are not in any pain. However, when these medications are used to treat physical pain, it is extremely unlikely that patients will become addicted to them. Addiction is a psychological problem that very rarely affects people who take opioids for pain control. "Feeling high" from opiates does not happen to people who take them for pain control. However, pain-free people who abuse opioids for fun can run into problems with addiction.
Other cancer pain treatments
For the most part, cancer pain is treated with pain medications. Occasionally, other methods can be employed – either in addition to medications or instead of them.
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. Other approaches to pain control include muscle relaxation, massage, use of heat and cold, and guided imagery. Usually, these techniques are incorporated into a treatment plan that includes narcotic pain medications, and they aren't commonly employed alone.
Acupuncture may be effective for people who experience pain related to cancer or cancer treatments. There are a number of scientific studies that have supported the use of acupuncture in this area. If you consider acupuncture, make sure to consult a licensed practitioner as rigorous training and experience is required for proper application of this technique.
There are a few techniques for treating pain that are more invasive than medications. If a patient cannot tolerate narcotics, or has pain that cannot be adequately managed with narcotics, there are certain procedures that can be utilized. These procedures are not commonly employed, but can of tremendous benefit to a small subset of people with unrelenting cancer pain.
Anesthesiologists are capable of injecting long acting numbing medications directly into nerves that are carrying pain signals. They can also inject alcohol into nerves to temporarily deaden them. This can provide good pain relief, but is usually associated with numbness. A potential drawback of these approaches is that many of the nerves that carry pain signals are also used to control movements of a particular body part. If the nerves controlling muscles are damaged or numbed, this can cause muscle weakness or even paralysis. In the most severe pain cases, surgeons can actually cut nerves or even parts of the spinal cord. These are permanent procedures that often cause many severe side effects. None of these approaches should be undertaken lightly, because the potential for unwanted side effects and permanent damage is high. Make sure and speak with your doctors and surgeons at length before you consider trying any of these procedures. Generally, these techniques should be thought of as a "last resort" after everything else fails.
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