Cancer pain is a common complication of cancer diseases. Because of the chronic and progressive nature of the disease, cancer pain is a common cause of chronic pain. Cancer pain results from tissue damage – either due to the disease itself, or due to treatment (chemotherapy, radiotherapy). The principles of management of cancer pain include:
Treatment of the cancer
Providing information, counselling and support to the patient
Effective treatment of the pain
Setting realistic goals for pain management
Pain is a common symptom in patients with cancer, with one-third experiencing pain at diagnosis and two thirds experiencing pain with advanced cancer. Treatment for cancer pain will vary between patients, as different patients may experience different levels of pain even if they have the same form of cancer.
Types Of Cancer Pain
Somatic pain is the result of activity by pain receptors in the deep tissues of the body, or on the surface. An example of deep tissue pain would be that of cancer that has spread to the bone. The site of pain cannot be pinpointed and has a dull, achy feeling. An example of surface pain is a pain at a surgical incision site. People describe this pain as being sharp and possibly having a burning sensation.
Neuropathic pain is often described as a burning or tingling sensation. It is caused by injury to the nervous system. The injury can include a tumour putting pressure on the spinal cord or nerves. Chemotherapy or radiation can also cause chemical damage to resulting in pain.
Viscera are internal organs contained in a cavity of the body, like the chest, abdomen, and pelvis. So, visceral pain is pain felt in one of these areas caused the activity of pain receptors in these areas.4 In cancer, the activation of pain receptors can be caused by a tumour putting pressure on one or more of the organs, the stretching of the viscera, or the general invasion of cancer. This type of pain is described as having a throbbing, pressured sensation. Once the type of pain has been established, then it is categorized into either acute pain or chronic pain.
Acute pain refers to pain that is short-lived and the cause can be easily identified such as an activity causing such pain. Acute pain can come and go and may increase over time.
Chronic pain lasts longer than three months. Physicians often have a tough time treating chronic pain as it is often hard to describe.
Refractory pain means pain that continues or worsens despite attempts at treatment. It is not uncommon among cancer patients. Some risk factors for refractory pain include:
Multiple pains and pain mechanisms
Long-standing pain or pain resistant to medication
Poor response to analgesics in the past
Adverse effects of analgesics
History of drug and alcohol dependency
Pain Wind-up- With time, cancer pain can increase in some patients – either due to progression of the disease (with new sites involved), or due to a phenomenon called ‘pain wind-up’. Pain wind-up is the phenomenon where patients require increasing doses of opioids (a type of pain-relieving medication) over a short period of time or have rapidly increasing pain scores over a short period of time (for example, from a pain score of 0 (no pain) to a score of 10 (worst pain ever felt)). Pain wind-up is a type of opioid-insensitive pain – opioids will not relieve pain wind-up. The cause of pain wind-up is usually inadequate treatment of pain or misdiagnosis of neuropathic pain. Pain wind-up can usually be prevented by correct pain diagnosis and aggressive use of pain-relieving medications together with clear precise explanations given to you, the patient.