Cancer pain: is it treatable? Facts & Fictions

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Overview

Pain is the result of a physiological series of electrical and chemical events that occur in the body. The International Association for the Study of Pain defines pain as “an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage.”

Pain receptors are bare nerve endings that are widely distributed throughout the body in the skin and mucous membranes. 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.

Pain depends on many factors such as the type of cancer, the stage of the disease, and the patient’s tolerance. Cancer pain can result from the following:

  • Blocked blood vessels causing poor circulation
  • Bone fracture from metastasis
  • Infection
  • Inflammation
  • Psychological or emotional problems
  • Side effects from cancer treatments (e.g., chemotherapy, radiation)
  • Tumor exerting pressure on a nerve

Initially, pain may produce physiological signs such as grimacing, rapid heart rate, sweating, and rapid breathing. Patients with pain lasting more than 3 months (chronic pain) often do not display physiological signs and as a result, chronic pain often is undertreated. Communication between the patient and physician is important to ensure adequate pain relief.

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.

Incidence and Prevalence

Studies have shown that 90% of patients with advanced cancer experience severe pain and that pain occurs in 30% of all cancer patients, regardless of the stage of the disease. As many as 50% of patients may be undertreated for cancer pain, yet not all cancer patients feel pain, and pain is rarely a sign of early cancer. Pain usually increases as cancer progresses.

The most common cancer pain is from tumors that metastasize to the bone. As many as 60-80% of cancer patients with bone metastasis experience pain.

The second most common cancer pain is caused by tumors infiltrating the nerve and hollow viscus. Tumors near neural structures may cause the most severe pain. The third most common pain associated with cancer occurs as a result of chemotherapy, radiation, or surgery.

Cancer pain also may occur in different parts of the body. In one study, more than 80% of patients experienced two distinct pains, and more than 30% experienced three distinct pains.

Chronic Cancer Pain

Effectively treating chronic pain poses a great challenge for physicians. This type of pain often affects a person’s life in many ways. It can change someone’s personality, ability to function, and quality of life.

According to the American Cancer Society, chronic cancer pain may involve persistent pain and breakthrough pain. Persistent pain is continuous and may last all day.

Breakthrough pain is 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.

Breakthrough cancer pain can result from the cancer or cancer treatment, or it may occur during a certain activity (e.g., walking, dressing, coughing). It also can occur unexpectedly, without a preceding incident or clear cause. Breakthrough pain usually is treated with strong, short-acting pain medications that work faster than persistent pain medications.

Some facts about cancer pain:

  • 10 lakh new cancer patients are diagnosed every year in India.
  • 60% are diagnosed in advanced stage, so require only pain management and palliative care.
  • 30%-50% have pain at the time of diagnosis.
  • 70% to 90% have severe pain when the disease is advanced.
  • 40% die with severe pain.
  • 60%-80%complains of inadequate pain relief by their physician.
  • 30% are not relieved by drug treatment alone, so require interventional pain management.
  • More than 90% cancer pain can be adequately controlled.

From the above statistics it is seen that cancer pain is inevitable at some stage of the disease, but at the same time 90% of the cancer pain are curable by some means or other.

What are the reasons then for inadequate cancer pain control? Why most of the cancer patients are suffering from cancer pain at some stage of the disease?

The most important reason is lack of awareness.

Lack of awareness exists among:

  1. Health care workers (including doctors)
  2. Policy makers
  3. Public (patients and their relatives) that cancer pain can be cured or controlled.

There are other reasons also, like: lack of financial resources, lack of infrastructure, lack of adequately trained personnel who can perform interventional pain management; fear among treating physician about drug dependency, and drug abuse, and of course non-availability of opioids due to legal restriction.

Why the cancer pain must be properly controlled?

Apart from being excruciating and intolerable in nature there are other reasons to control the cancer pain.

  • Cancer pain is curable; at least it can be controlled.
  • Psychological effects of cancer pain can be avoided. (anxiety, depression, lack of sleep, anger, suicidal attempts)
  • Precipitation of diseases like diabetes, hypertension can be avoided.
  • Meaningful and productive social life can be lived.
  • Effective pain control can prolong life.
  • Relatives also relieved from constant worries.

What are the ways to treat the pain?

The methods of treatment of cancer pain are many like:

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  1. Pharmacotherapy (treatment with oral or injectable pain killer medicines) with analgesics (opioid & non-opioid); co-analgesics (anti-depressant & anti- convulsant) and others.
  2. Interventional pain management (IPM) WHO recommendations: (same protocol is applicable for the other kinds of pain too)
  3. Stage analgesic ladder (Pharmacotherapy).
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  • 1st stage- NSAIDs +/- NSAIDs
  • 2nd stage-Weak opioid +/- NSAIDs
  • 3rd stage-strong opioid +/- NSAIDs
  • Interventional pain management (IPM) in 4th stage +/- NSAIDs.

What are the indications of Interventional pain management in cancer patients?

  • Severe pain that is expected to persist
  • Failure of analgesic drug treatment
  • Non-availability of morphine
  • Limited life expectancy
  • Well localized pain
  • Pain is not multi-focal in origin
  • Pain is of visceral or somatic in origin
  • Coexisting or preexisting problems curable with IPM

Role of interventional pain management specialist.

Pain Management Specialist is valuable resource in pain physiology/ pharmacology & providing additional treatments.

  • Not operative, office based interventions
  • Diagnosis
  • Thorough assessment of patient
  • Management of all types of pain
  • Adjustment of dose & side effects

Types of Interventional pain management in cancer patients

  • Neurolytic procedures.
  • IPM done in non-cancer pains.
  • Advanced interventional pain management.

What is neurolysis?

It is a procedure (a type of IPM) by which nerve fibres carrying nociception (pain sensation) is irreversibly destroyed to obtain permanent pain relief.

Methods of neurolysis (neuro destructive):

Neurolysis can be done by applying neurolytic agents like: phenol, alcohol, hypertonic saline, glycerin etc on particular nerve fibres.

Some other methods like:

  • Cryoneurolysis (neurolysis by applying cold)
  • Radiofrequency ablation (neurolysis by applying heat)
  • Neurectomy (neurolysis by operation)