What is Cancer?
Cancer is a leading cause of death worldwide, accounting for approximately 8.8 million deaths in 2015. Among the various comorbidities occurring in cancer patients, pain is one of the most common symptoms. It has a negative impact on the patient’s functional status and quality of life, and may be experienced at the time of diagnosis, during active treatment, or after treatment has ended. According to a World Health Organization report, pain occurs in 20% to 50% of patients with cancer and roughly 80% of patients with advanced-stage cancer experience moderate to severe pain.
What is Cancer Pain?
Cancer patients often have multiple sites of pain that can be acute or chronic. Pain in patients can be assessed using the NRS (Numeric rating scale). Cancer pain has been rated from 4 to 6 (severe) and with exacerbation as high as 7. Acute pain can occur due to damage caused by an injury or after having an operation and tends to last for a shorter period. The pain goes as the wound heals or by taking painkillers. Chronic pain results from nerve damage that occurs during surgery and radiation therapy. Some chemotherapy drugs can also cause weakness, numbness, and pain, mostly in the hands and feet. It continues for a long time after injury or treatment.
What Causes Cancer Pain?
Cancer pain can be due to a variety of reasons. It may occur as a result of cancer itself or due to the cancer treatment. Some of the main reasons include:
Tumor suppression – As a tumor grows it may put pressure on the nerves, bones or organs leading to pain.
Infusion-related pain syndrome – The infusion of intravenous chemotherapy may cause four types of pain syndromes including venous spasm, chemical phlebitis or chemical injury and inflammation to the veins (from potassium chloride and hyperosmolar solutions), vesicant extravasation (when the drugs or vesicants leak out of the veins and cause tissue injury), and anthracycline-associated flare.
Treatment-related mucositis Mucositis pain is a major unavoidable clinical problem associated with cancer treatment. It causes acute pain due to the shedding of the epithelium, inflammation of the mucosa, and ulceration. Severe mucositis often occurs as a consequence of high-dose chemotherapy that is used to kill cells in the bone marrow. Studies reveal that mucositis affects up to 100% of bone marrow transplant patients.
Musculoskeletal pain Many oncology patients are treated with Paclitaxel. This drug is found to develop a subacute pain syndrome that is commonly termed myalgia or arthralgia. Pain mainly originates in the back, hips, shoulders, thighs, legs, and feet. From the study it is inferred that this pain occurs as a result of sensitization of nociceptors or the spinothalamic system (sensory pathay from the skinto the thalamus).
Malignant spinal cord compression
If a tumor spreads to the bones of the spine, it can put pressure on the spinal cord causing spinal cord compression. This compression often leads to back or neck pain and can spread to the lower back and legs. It mostly occurs in certain cancers, including breast, lung and prostate cancer, lymphoma and myeloma.
What are the Types of Cancer Pain?
It is extremely important for your doctor to diagnose the type and cause of cancer pain. Depending on the type, the cancer pain management can be done.
Cancer-related neuropathic pain is a common type of cancer pain. It occurs in about 90% of patients receiving neurotoxic chemotherapy.
Bone pain frequently arises from metastases (spread) of breast, prostate and lung tumors. The tumor cells lead to bone destruction in a manner that they first contact, injure, and then destroy the sensory fibers. Both primary and metastatic bone cancer causes bone pain.
Visceral or soft tissue pain
Visceral pain is felt in the internal organs contained in a cavity like the chest, abdomen, and pelvis. The activation of pain receptors can be caused by a tumor suppression pressure on any of the organs, ultimately the stretching of the viscera.
Phantom pain is defined as a longer-lasting effect of surgery, beyond the usual surgical pain. Phantom sensations are the non-painful sensations experienced in the body from the part that no longer exists. For example, the feeling of pain in case of mastectomy. This pain is thought to occur as a result of hyper-excitability of NMDA receptors.
Breakthrough pain in cancer patients results out as transient exacerbation of pain occurring in a patient with otherwise stable, persistent pain. Reports show that it affects over 50% of patients, particularly those with moderate to severe background pain. It may occur during certain activities like walking, dressing, and coughing.
How do You Treat Cancer Pain?
Cancer pain management is a challenging task. Proper therapeutic approach helps treat cancer pain. Among the various types of treatment methods available for cancer pain surgery, chemotherapy, and radiation therapy are the most common. If these are not applicable depending on the patient’s situation then pain medications can usually control the pain. The pain medications generally include:
- Over-the-counter and prescription-strength pain relievers, such as Aspirin, Acetaminophen and Ibuprofen.
- Opioid painkillers are a common treatment for cancer pain. These include Morphine, Diamorphine, Fentanyl and Alfentanil, Buprenorphine, Hydromorphone, Codeine and Methadone. Opioid rotation involves changing from one opioid to another using correct equianalgesic conversion techniques in patients who do not respond to a particular opioid. It helps to achieve better analgesia with least side effects. Rotating to methadone in neuropathic pain has been reported. Topical application of opioids in some oral ulcerative cancer and non-cancer pain has been found to have positive effect. The presence of peripheral opioid receptors has also been found to play a role in it.
- Adjuvant analgesics are also used. There are different types of co analgesics such as steroids (Prednisone and Dexamethasone), bisphosphonates, tricyclic anti-depressants (Amitriptyline, Imipramine Doxepin, and Clomipramine) for mood elevation and sleep, anti-convulsants (Gabapentin) and local anaesthetics that are also used. In advanced cancer patients, antidepressants are beneficial when pain is accompanied with depression.
- Some alternative methods are also used when oral medication is not possible like injecting painkillers into the fluid around the spine, nerve block and strengthening painful bones (cementoplasty). Neuro-Ablative procedures. Use of neuroablative procedures in cancer pain relief is a useful technique in improving the quality of life in patients when compared to oral analgesics. It is defined as the physical interruption of pain pathways either surgically, chemically or thermally. Some of the procedures are celiac plexus block, endoscopic ultrasound guided celiac plexus neurolysis and Ganglion impar block.
- Other therapies such as acupuncture, acupressure, massage, physical therapy, relaxation, meditation and humor may also help to relieve pain.
- Mitigation of Phantom pain– Phantom pain that results due to hyperexcitability of NMDA receptors can be mitigated using Dextromethorphan (120 to 270 mg/day) that blocks NMDA receptors. A study shows about >50% decrease in pain intensity, mood elevation, and lower sedation in treatment phase.
How do You Overcome or Manage Cancer Pain?
Pain is a devastating symptom of cancer affecting the quality of life of patients and even families and caregivers. It includes physical, psychosocial, and emotional aspects so an adequate cancer pain management method should be opted to overcome it. Here are some ways to overcome cancer pain:
Proper assessment of pain
As cancer pain is a multidimensional symptom, proper assessment is a necessary step. Validated pain tools like VAS (Visual analogue scale), and NRS (Numerical rating scale) should be used to screen and measure pain intensity. Both scales are easy to use with most patients and show good psychometric properties. Another method is Edmonton Symptom Assessment System (ESAS). It has shown potential to improve clinical encounters and patient satisfaction. This tool is designed to assist in the assessment of nine common symptoms in cancer patients. They include pain, tiredness, nausea, depression, anxiety, drowsiness, appetite, well-being, and shortness of breath. It is a valid,and reliable assessment tool that provides a clinical profile of symptom severity over time.
Educating physicians and health care professionals
Lectures on pain management and palliative care for students and trainees should be done. Interdisciplinary pain management rounds should also be conducted to discuss patient cases. According to a report, the evaluation of pain education was better for physicians who had received education and training recently than for older physicians.
Complementary and alternative methods
Managing cancer pain involves both pharmacological and non pharmacological interventions. The other methods can be:
- Acupuncture – It is an accepted scientific treatment method that helps the body restore its balance by means of stimulating some specific points on the body with the help of needles. A randomized study shows that acupuncture is very effective in relieving joint pain and stiffness.
- Massage – This is a manual technique that involves application of pressure and traction on the body’s soft tissues via peripheral receptors. It is used for reducing pain, anxiety, and depression in oncological palliative care patients.
- Reflexology – It involves the use of manual pressure applied to specific areas, or reflex points of the feet that are considered to correspond to other body areas or organs. It relieves stress and thereby reduction in pain perception.