Up to 25% of people have pain during early, localized cancer, and up to 90% of people have pain as cancer progresses to the advanced stage. Because there may be new pain or progressively increasing pain, frequent re-evaluation is necessary to optimize therapy. People with cancer often fear being in pain, but cancer pain can be controlled, or at least reduced, for most people.

Causes of cancer pain

Pain related to cancer may arise from nerves or from any tissues or organs in the body, causing various pain syndromes. The pain may be related to cancer itself (for example, as the tumour grows it can press on nerves and other tissue, and cancer may spread to the bones), or it may be caused by anticancer therapy or due to unrelated conditions.

Treatment of cancer pain

Fortunately, the majority of people with cancer pain will experience pain relief with analgesics (pain medications or painkillers). But some will need additional treatments such as surgery, radiation or chemotherapy to reduce the size of the tumour, or other medications to obtain satisfactory pain control. Cancer pain treatment is individualized and depends on the type of cancer, the type of pain being treated, and overall health.

Analgesics remain the most widely used treatment for cancer pain. The most commonly used medications include non-opioid medications (e.g., acetaminophen, NSAIDs -nonsteroidal anti-inflammatory drugs, and corticosteroids) and opioids (narcotics).

Non-opioids: Non-opioid pain medications, including acetaminophen and NSAIDs (e.g., naproxen, diclofenac), are used to treat mild to moderate cancer pain. Acetaminophen helps reduce pain and is safe when used in usual doses. Too much acetaminophen; however can cause liver problems.

NSAIDs help with pain and inflammation but are not the best choice for some people (e.g., people with severe heart disease or bleeding ulcers in the stomach or intestines). Side effects with NSAIDs include stomach upset, and rarely, bleeding in the stomach. Corticosteroids (e.g., dexamethasone, prednisone) are primarily used to reduce swelling and inflammation but can cause stomach upset, changes in blood sugar, and fluid retention.

Opioids: Opioids (e.g., morphine, hydromorphone, oxycodone, fentanyl) are used to treat moderate to severe cancer pain. These medications act primarily in the brain and spinal cord where they inhibit the transmission of pain impulses. No "ceiling effect" is evident - in other words, pain relief can be reached with a high enough dose. The optimal opioid dose is the dose that relieves pain without intolerable side effects.

Pill form is the preferable route for receiving opioids, but subcutaneous (under the skin) injections or infusions (constant supply of medication), intravenous (into a vein) injections and infusions, suppositories, or patches applied to the skin may also be used.

When pain is constant, opioids should be given on a regular (around-the-clock) basis. It is easier to manage pain when it is kept under control. Short-acting opioids are used initially until the optimal daily dose of the opioid is determined. After this, a long-acting formulation may be added for more even pain control. Short-acting opioids will continue to be used for "breakthrough" pain - when increased pain is experienced despite regular doses of opioids. The goal is to maintain a constant, steady level of opioid in the body to control pain before it is felt.

Depending on the type of caner, other medications may be used to control cancer pain, including:

  • Antidepressants or antiseizure medications to help nerve-related pain.
  • Bisphosphonates to inhibit bone loss, which in turn can reduce pain due to cancer that has spread to the bone.
  • Radioisotopes such as strontium-89 for bone pain

Other techniques for relieving pain

Invasive techniques achieve pain relief by blocking or modulating the transmission of pain impulses along the nerves. This interruption of impulses can be done using peripheral nerve blocks or spinal or epidural analgesia. These are technical procedures in which a needle is inserted near a nerve and local anesthetic agents are injected. These procedures stop pain messages from reaching the spinal cord and can give complete relief by anesthetizing an area. However, the relief lasts only a short amount of time so these techniques are most useful for obtaining rapid pain relief while other treatments are started. Direct administration of opioids into the cerebrospinal fluid can also be considered for severe pain.

The cutting or destruction of nerve pathways is usually reserved for localized, uncontrolled pain. Radiation therapy is very effective for relieving localized pain. However, repeat radiation may be limited because of side effects to the surrounding tissues.

What you can do

There are many options for the treatment of cancer pain and someone with cancer should expect to be comfortable. If you or a loved one has cancer and is in pain, talk to your doctor about what pain control strategies would be most suitable. Make sure you communicate with your health care team about how well treatment strategies are working and if you have any side effects. Don't change how you are using your medications without talking to someone on your health care team.