Cancer Pain – What Is It, How Does It Occur and How Is It Treated?

Pain can be treated effectively in most patients with cancer or a history of cancer. Even if cancer-related pain does not disappear completely, treatment-related pain can be relieved in almost all patients. Effectively relieving or alleviating pain and other complaints improves quality of life at all disease stages. Patients should tell their doctors or nurses whether they have pain. It is important that patients provide information about any pain they may experience.

What Is Cancer Pain?

Cancer pain can be defined as a complex sensation reflecting both damage to the body and the body’s response to that damage . Although doctors agree that controlling cancer pain is a high priority, pain is not always properly understood or treated.

Pain is one of the most common and most feared complaints in cancer patients. Despite advances in cancer medicine, the frequency of cancer-related pain has not decreased over the years. On average, %60 of cancer patients experience cancer-related pain at some point during their illness.

Insufficient importance is given worldwide to cancer-related pain. Although modern medicine offers many pain-relieving drugs and interventional methods,  half of patients suffering cancer-related pain receive inadequate treatment.

How Does Cancer Pain Occur and What Causes It?

Physical cancer pain has two sources:

• Nociceptive pain refers to conventional pain in which damage to a part of the body is transmitted by nerves. This sensation is generally felt as aching or pressure – most cancer pain feels this way.
• Neuropathic  pain refers to pain caused by damage within the nervous system. It is often felt as sharp burning, stabbing, abnormal sensation and tingling. Prolonged use of chemotherapies such as paclitaxel and oxaliplatin causes neuropathic pain.

The experience of pain is generally a combination of different pain types. Pain can worsen through fear of pain itself or of becoming ill.

People may experience intense, short-term acute pain or long-term chronic pain from cancer. Pain may also be part of  a cancer pain syndrome . Cancer pain syndromes can be caused by tumors involving:

• invasion of soft tissue or bone (including bone fractures)
• compression of nerves or blood vessels by a tumor
• obstruction of hollow organs such as the intestines
• bleeding into a tumor

Cancer pain syndromes may also arise from substances (hormones, proteins) produced by cancers that affect the function of other tissues and organs. Cancer pain syndromes can also occur after surgery, radiation therapy or chemotherapy.

Identifying the cause of pain is important because knowing the cause makes pain easier to manage. Whether or not the cause is known, pain should always be treated appropriately. If pain is not adequately treated in the short term, it can worsen and become harder to control later.

Assessment of cancer pain is an ongoing process requiring continuous attention to pain. New pain or changes in the pain pattern may indicate minor, treatable problems. However, changing pain is often a sign of growing disease. Because cancer pain treatment is based on treating the disease causing the pain, identifying the causes of any new pain is extremely important.

The greatest barrier to treating cancer pain is inadequate pain assessment.

Assessment of Cancer Pain

Because cancer types, stages, patients’ responses to pain and treatment, and personal preferences differ, cancer pain management should be individualized. All patients should be screened regularly for pain. If pain is present, inpatients should be asked more frequently and encouraged to notify a nurse or doctor. Pain intensity is assessed on a scale from 0 to 10; numbers between 0, “no pain,” and 10, “worst pain,” can be used. Necessary interventions, such as providing adequate analgesics (painkillers), should be performed, and patients should be encouraged to inform their nurses or doctors whenever pain occurs.

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How Is Cancer Pain Treated?

Scientific advances in molecular biology, neuroscience, pharmacology and anesthesiology have brought substantial progress in understanding and treating pain, especially over the last thirty years. Researchers have identified pain receptors and explained how pain signals are transmitted to the brain. These laboratory findings have translated into more effective therapies for pain in cancer patients.

Cancer-related pain can be treated with one or more of the following approaches:

• Eliminating the cancer surgically or removing as much of the tumors as possible, or
• Achieving significant pain relief by partially or completely treating the underlying cancer with radiotherapy, chemotherapy and immunotherapy, 
• Drugs directed specifically at pain, and interventional and noninterventional complementary methods.

Palliative Surgery / Radiation Therapy

Radiotherapy can certainly be given for palliative purposes, such as reducing pain and other complaints to maintain patients’ quality of life. Surgery can be performed to prevent or control painful cancer complications, such as bowel obstruction, compression of the spinal cord or peripheral nerves, or compression of organs. Palliative surgery and radiotherapy focus on patient comfort, and patients with advanced cancer most often need these approaches.

Pharmacological and anesthetic approaches

Pain-relieving drugs can be given for various cancer-related pains. These drugs are administered according to patients’ preferences and individual choices.

These include:

• Orally as tablets
• Transmucosally (held briefly in the mouth for absorption)
• Rectally (a suppository through the anus)
• Intravenously (through a vein as an infusion)
• Subcutaneously (injection just beneath the skin) 
• Transdermally (absorbed through the skin) 
• Epidurally or intrathecally (into the area around the spinal cord)

Approach to Cancer Pain According to Severity

Mild and Moderate Pain

Drugs such as aspirin and ibuprofen, nonsteroidal anti-inflammatory drugs , and nonopioid painkillers such as paracetamol help relieve many mild-to-moderate pains, including muscle and bone pain.

Also called narcotic analgesics, opioids, are more potent painkillers sold with red and green prescriptions. The nonopioid analgesics listed above can be given with opioids and other treatments to relieve more severe pain.

Severe Pain

Opioids (such as morphine, fentanyl, codeine, oxycodone, hydromorphone and methadone) are highly effective at relieving or reducing cancer pain. The best-known drug in this group is morphine, and contrary to common belief, morphine is not the strongest opioid. Patients sometimes fear these drugs will cause addiction; however, these drugs are safe and well tolerated. Through biotechnological methods, they are transformed into chemicals directed more toward pain and distress relief than pleasure. Opioids rarely cause addiction when taken appropriately.

Depending on need, opioids may be prescribed for cancer pain of any severity. For moderate or more severe pain, they may be given with or without paracetamol or nonsteroidal anti-inflammatory drugs. Your doctor will closely monitor and adjust the amount of opioid used according to your needs.

Sudden Severe Pain (breakthrough pain)

Cancer patients are known to experience intermittent sudden severe pain during the day. These situations require fast-acting, easily administered painkillers. For such pain, your doctor may prescribe a fast-acting analgesic such as morphine taken orally as a tablet. These rescue doses act quickly. They are usually given in addition to medication administered regularly for routine pain.

Adjuvant Analgesics

Certain drugs, particularly antidepressants, anticonvulsants and steroids, are known to benefit cancer pain. These drugs help alleviate pain caused by tingling and burning sensations in the extremities and by inflammation.

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Nerve Blocks

For acute (sudden-onset) and postoperative pain, and some chronic pain problems, temporary nerve blocks may provide relief. These are usually performed by injecting a local anesthetic around nerves. The anesthetic blocks pain signals to the brain, producing rapid pain relief. These techniques can be applied with temporary or permanent durations planned. They are performed by interventional radiologists, anesthesiologists or pain medicine specialists.

Epidural and intrathecal pumps: These are most often preferred when there is a severe, continuous need for painkillers or pain cannot be controlled with oral pain medication. Epidural or intrathecal pumps are carried in a pouch or placed under the skin. This allows continuous drug delivery.

Neurosurgical Approaches

Most cancer-related pain can be managed effectively with medication, but if drug treatment does not provide sufficient relief or side effects become a problem, nonpharmacological approaches are often effective.

When pain cannot be controlled, neurosurgical techniques may be applied by disabling nerves in the spinal cord responsible for transmitting pain signals to the brain.

Psychological Approaches

Short-term psychotherapy, structured support and cognitive-behavioral therapy may increase treatment effectiveness by improving patients’ coping skills. For the major psychiatric complications of cancer and its treatment, psychiatric support may be obtained for assessment and recovery.

Complementary Treatments

Complementary approaches for pain problems can be incorporated at any stage of treatment. These include relaxation techniques, meditation, movement therapies, acupuncture, art therapies and massage for medical pain control (reflexology). These techniques may help alleviate acute pain, pain following an acute episode and certain forms of chronic pain.