Advanced Reading: Treating Cancer Pain

Basic Principles of Cancer Pain Management

The World Health Organization developed a 3-step approach for pain management based on the severity of the pain:

• For mild to moderate pain, the doctor may prescribe a Step 1 pain medication such as aspirin, acetaminophen, or a nonsteroidal anti-inflammatory drug (NSAID). Patients should be monitored for side effects, especially those caused by NSAIDs, such as kidney, heart and blood vessel, or stomach and intestinal problems.
  
  
• When pain lasts or increases, the doctor may change the prescription to a Step 2 or Step 3 pain medication. Most patients with cancer-related pain will need a Step 2 or Step 3 medication. The doctor may skip Step 1 medications if the patient initially has moderate to severe pain.
  
  
• At each step, the doctor may prescribe additional drugs or treatments (for example, radiation therapy).
  
  
• The patient should take doses regularly, "by mouth, by the clock" (at scheduled times), to maintain a constant level of the drug in the body; this will help prevent recurrence of pain. If the patient is unable to swallow, the drugs are given by other routes (for example, by infusion or injection).
  
  
• The doctor may prescribe additional doses of drug that can be taken as needed for pain that occurs between scheduled doses of drug.
  
  
• The doctor will adjust the pain medication regimen for each patient's individual circumstances and physical condition.
  

Acetaminophen and NSAIDs

NSAIDs are effective for relief of mild pain. They may be given with opioids for the relief of moderate to severe pain. Acetaminophen also relieves pain, although it does not have the anti-inflammatory effect that aspirin and NSAIDs do. Patients, especially older patients, who are taking acetaminophen or NSAIDs should be closely monitored for side effects. Aspirin should not be given to children to treat pain.

Opioids

Opioids are very effective for the relief of moderate to severe pain. Many patients with cancer pain, however, become tolerant to opioids during long-term therapy. Therefore, increasing doses may be needed to continue to relieve pain. A patient's tolerance of an opioid or physical dependence on it is not the same as addiction (psychological dependence). Mistaken concerns about addiction can result in undertreating pain.

Types of Opioids

There are several types of opioids. Morphine is the most commonly used opioid in cancer pain management. Other commonly used opioids include hydromorphone, oxycodone, methadone, and fentanyl. The availability of several different opioids allows the doctor flexibility in prescribing a medication regimen that will meet individual patient needs.

Guidelines for Giving Opioids

Most patients with cancer pain will need to receive pain medication on a fixed schedule to manage the pain and prevent it from getting worse. The doctor will prescribe a dose of the opioid medication that can be taken as needed along with the regular fixed-schedule opioid to control pain that occurs between the scheduled doses. The amount of time between doses depends on which opioid the doctor prescribes. The correct dose is the amount of opioid that controls pain with the fewest side effects. The goal is to achieve a good balance between pain relief and side effects by gradually adjusting the dose. If opioid tolerance does occur, it can be overcome by increasing the dose or changing to another opioid, especially if higher doses are needed.