Cancer Pain – Part 1: Symptoms and Types of Pain

This is what Dr. Patrick Dixon wrote about cancer pain (in: As a doctor who has cared for the dying I have often been asked to kill people. One reason is that the fear of pain is usually greater than the fear of death itself. All of us have relatives or friends who have died of cancer, and many of us have traumatic memories of a painful deterioration. What is scandalous is that in almost every case their suffering was largely preventable and unnecessary, inflicted not by the disease but by shocking medical ignorance, arrogance, complacency and pride.

Pain is one of the most common problems faced by cancer patients. It is directly or indirectly caused the cancer.
Basic Theory

Pain is the result of a physiological series of electrical and chemical events that occur in the body. When pain receptors are triggered by mechanical, chemical, or thermal stimuli, the pain signal is transmitted through the nerves to the spinal cord and then to the brain.
Initially, pain may produce physiological signs such as grimacing, rapid heart rate, sweating, and rapid breathing. Patients with chronic pain (lasting more than 3 months) often do not display physiological signs and as a result, chronic pain often is under treated.
A complex array of psychological and emotional variables play a role in the suffering that a patient with cancer pain experiences. The level of emotional distress that a cancer pain patient feels varies individually, depending on many factors such as personality and family support. It is estimated that 25% of all cancer patients show signs of clinical depression, with the percentage increasing to greater than 70% for patients with advanced stages of the disease. Untreated pain leads to many cancer suicides.

When possible, cancer pain is treated by removing or reducing the tumor that is causing it. When the tumor cannot be removed, the pain can be treated in various ways.
What You Need to Know About Pain

Studies have shown that:
·         90% of patients with advanced cancer experience severe pain
·         30% of all cancer patients suffer pain, regardless of the stage of the disease.
·         As many as 50% of patients may be under-treated for cancer pain.
·         Not all cancer patients feel pain, and pain is rarely a sign of early cancer.

·         Pain usually increases as cancer progresses.

Why There is Pain

1.      Pain in the bones due to metastases.
2.      Pain from the pressure of the cancer growth or tumour pushing against internal organs.
3.      Pain from infection, swelling and inflammation associated with the tumour.
4.      Pain from blockage: examples, blockage of the stomach, blockage of a blood vessel.
5.      Pain that occurs when a tumour compresses a nerve, which can also cause numbness or paralysis.
6.      Pain due to psychological or emotional problems.

7.      Pain as the result of the side effects from cancer treatments (e.g., chemotherapy, radiation).

Symptoms of Cancer Pain

The most common pains are back pain, headache and limb pain.
1.      People with brain metastases may have generalised headache (all over their head) that often occurs during sleep and gradually becomes more severe, as well as poor mental status and leg weakness.
2.      Back pain can occur with bone metastases, which can often occur in people with cancer of the prostate, kidney, breast, lung cancer, muscle (myeloma) or skin. Bone pain has been described as dull and aching, except when it is associated with muscle spasms, in which case the pain may be sharp and excruciating.Compression of the spinal cord occurs in some bone metastasis patients and is often excruciatingly painful.Cancer cells may spread into the fluid in the spine, causing neck and back pain, and stiffness amongst other symptoms.2
3.      Cancer treatments may cause pain, for example stomach pain if they affect the stomach. Radiotherapy may cause burning pain on the skin, and chemotherapy may cause painful sores in the mouth.

Pain can be persistent pain, i.e. continuous and may last all day; or breakthrough pain, i.e., a brief flare-up of severe pain that occurs even while the patient is regularly taking pain medication. It usually comes on quickly and may last from a few minutes to an hour. Many patients experience a number of episodes of breakthrough pain each day.

Types of Pain

There are three types of pain: somatic, visceral and neuropathic.
Somatic pain: is caused by the activation of pain receptors in either the body surface) or deep / musculoskeletal tissues). Common causes of somatic cancer pain include metastasis in the bone and post-surgical pain from a surgical. Deep somatic pain is usually described as dull or aching but localized. Surface somatic pain is usually sharper and may have a burning or pricking quality.
Visceral pain: is caused by activation of pain receptors resulting from infiltration, compression, extension, or stretching of the thoracic (chest), abdominal, or pelvic viscera. Common causes of visceral pain include pancreatic cancer and metastases in the abdomen. Visceral pain is not well localized and is usually described as pressure-like, deep squeezing.

Neuropathic pain is caused by injury to the nervous system either as a result of a tumor compressing nerves or the spinal cord, or cancer actually infiltrating the nerves or spinal cord. It also results from cancer treatment (chemotherapy, radiation, surgery). This type of pain is severe and usually described as burning or tingling.