Cancer Pain

Causes, types, and treatment options

The Phenomenon of Cancer Pain

Pain is usually the chief complaint in patients presenting to a doctor’s office. The same applies to every patient diagnosed with cancer, as pain is a sign that can be used to determine whether cancer is present or getting worse.

Today, a large number of patients experiences cancer pain. In particular, 64% of cancer patients report experiencing pain at all stages of the disease, while 59% of patients report feeling pain while receiving therapy. Even after treatment, 33% of patients report pain.

World Health Organization (WHO) considers pain relief to be a critical humanitarian need. When paired with oncology treatments, the numerous alternatives for pain medications and interventional therapies can significantly reduce suffering and enhance patients’ Quality of Life.

However, it is estimated that only about 10%-15% of pain patients receive adequate pain management, while the remaining percentage receive poor management, especially in their last stage of life.
In many cases, cancer pain is treated exclusively with medication by the patient’s oncologist, while minimally invasive techniques and alternative techniques are either delayed or omitted. Consequently, patients are not receiving an holistic treatment that will most effectively contribute to pain relief.


Cancer pain may be the result of:

  • Direct tumor infiltration of organs and tissues
  • Side effects of diagnostic or therapeutic interventions (biopsy, radiation therapy, chemotherapy)
  • Pain unrelated to the disease or its treatments (e.g., back pain, headache, etc.).

The pain can be typical physical (tissue damage), visceral, neuropathic (central or peripheral nervous system damage) or a combination of the above, i.e., mixed pain.

Causes and Types of Cancer Pain

Neuropathic pain in oncology patients

Neuropathic pain is one of the most common forms of chronic pain and is the result of organ failure or dysfunction of the nervous tissue. This type of pain frequently affects cancer patients and may be caused by chemotherapy, radiation therapy, or even surgical procedures.

The most typical surgical procedures that cause neuropathic pain include:

  • Post-mastectomy pain syndrome (phantom limb pain)
  • Post-thoracotomy pain syndrome
  • Painful polyneuropathy
  • Radiation-induced fibrosis of the humerus or lumbosacral or other plexuses

Breakthrough pain

Even in patients with stable and well-controlled pain, breakthrough pain (also known as paroxysmal pain) can manifest as a transient pain flare-up. The main causes are tumor effect, antineoplastic therapy, and comorbidities.

Breakthrough pain is characterized by multiple episodes throughout the day, with a rapid onset and an average 30-minutes duration, given that the patient is receiving adequate treatment for their stable cancer pain.

About 40%-80% of cancer patients experience this type of pain, which has a substantial detrimental impact on their Quality of Life. Unfortunately, even today that we are aware of its existence, 2/3 of patients do not have satisfactory control of their breakthrough pain.

Goals and treatment principles of cancer pain:

  • Identification and immediate assessment of pain
  • Investigating mental and cognitive effects on pain perception
  • Adjusting analgesic treatments according to patient needs and tolerance
  • Maximizing patient level of autonomy and overall Quality of Life
  • Supporting and motivating family members
  • Review of outcomes on a regular basis

Key Treatment Principles and Goals

The need for pain treatment among patients must be acknowledged and given top priority by all healthcare professionals, especially in the field of Oncology.
Since cancer pain is complex and always evolving, its effective management necessitates commitment and constant evaluation. For a comprehensive approach to their pain, cancer patients should consult chronic pain clinics.

A key principle in cancer pain treatment is good and in-depth knowledge of the pathophysiology of pain, knowledge of the pharmacology of pain medications, as well as knowledge of all the approaches/methods of cancer pain management.

A three-level scale was established back in 1986 by the World Health Organization (WHO) as an international standard for cancer pain management. According to this scale, appropriate pain management offers adequate analgesia in 90% of cancer patients and more than 75% of end-of-life patients. Over the last years, however, the scale seems to have some shortcomings, as in the case of metastases-induced bone pain. As a result, the scale now has a 4th level that encompasses minimally invasive techniques.

Treatment Options

Cancer pain is managed with appropriate medication (a combination of drugs), minimally invasive techniques, or a combination of both.

Pain Medications

Pain medications are available in a variety of formulations and include:

  • Paracetamol and NSAIDs
  • Mild opioids (tramadol, codeine)
  • Strong opioids (morphine, fentanyl, methadone)
  • Anticonvulsants/Antidepressants
  • Corticosteroids

Minimally Invasive Techniques

  • Nerve block
  • Radiofrequency (RF) neurolysis of nerves, sympathetic ganglia, and plexuses
  • Alcohol- or phenol-block of sympathetic plexuses (stellate ganglion, abdominal plexus, etc.)
  • Epidural drug injection
  • Implantable pump for continuous subarachnoid drug infusion

Adjunct Treatments

  • Acupuncture
  • TENS
  • Physiotherapy
  • Nutrition