Cancer Pain - A Menacing Condition

Pain due to cancer may either be due to the medical interventions for the treatment of the disease or due to the tumor itself. Tumors can cause excruciating pain due to nerve irritation, nerve damage or activation of specialized pain-sensitive nerve fibres.

Treatments like chemotherapy or radiotherapy can sometimes cause pain even after the ailment is treated.

Approximately one in three cancer patients suffer from cancer pain, a condition that adversely affects their quality of life. Cancer pain is very common in the later stages of the disease. Generally, proper relief from cancer pain is achievable but there are certain hindrances to it such as drug shortage, faulty pain evaluation, addiction concerns, financial problems, etc.

In order to acquire proper pain control, it is essential to assess the type of pain (somatic, visceral or neuropathic) and the actual severity of pain. It is also imperative to recognize and identify the obstacles in the path of alleviation of cancer pain.

Here, the pharmacological opioid and nonopioid treatments of cancer pain are discussed:

Opioid Treatment:

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After examining the social, behavioral and psychological aspects of an individual, the therapist can focus on the pharmacologic therapies for the control of pain caused by cancer.

The World Health Organization (WHO) has formulated the analgesic ladder as an accepted guideline that involves the use of opioids as the chief ingredient of pharmacologic pain control therapy. It should be used in a stepwise approach depending upon the pain severity after regular pain assessment and monitoring. Besides opioids, nonopioid pain killers like acetaminophen and non-steroidal anti-inflammatory drugs (NSAIDs) are also widely available.

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Commonly used opioids are morphine and codeine. When pain is not relieved by acetaminophen or NSAIDs, opioids are used to control moderate-to-severe pain.

Since cancer pain is usually chronic and long lasting in nature, drugs with long half lives are the preferred choice of treatment.

Cancer pain is controlled in two steps. The first step involves baseline control while the second step is to control intermittent phases of pain. Extended-release formulations such as modified-release morphine, modified-release hydromorphone and modified-release oxycodone are used to serve the purpose.

The preferred route of administration is the oral route. For patients who find it difficult to tolerate morphine, transdermal administration is done.

An overdose of opioids can result in adverse side effects such as respiratory depression or death. An important point to remember is that rapid attainment of pain relief should not overshadow the person’s safety and should not pose a potential threat to his life.

Common side-effects of opioids are nausea, delirium, constipation, sedation, pruritus and respiratory depression. It is wise to anticipate these adverse effects beforehand and be careful while using opioid analgesics.

In about 50 percent of patients seeking opioids analgesics, constipation is reported due to suppression of intestinal movements and secretions.

With opioid administration, prophylactic laxatives should be given to avoid constipation.

Opioid-induced sedation is seen in about 23 to 28 percent of patients. It is believed that the inhibition of sensory input and disturbances in rapid eye movement (REM) are responsible for sedation. However, tolerance to opioid sedation is achieved in 2-3 days.

Nausea is reported in 60 percent cases. Other possible causes of nausea in cancer patients are uremia, constipation, hypercalcemia, anxiety, infection and chemotherapy.

Nausea can be treated with thiethylperazine, prochlorperazine, metoclopramide and haloperidol.

Itching or pruritus caused by opioids is seen in 50 percent patients. Antihistamines such as promethazine and diphenhydramine are effective in improving the distressing situation.

Pregabalin and gabapentin are the preferred choices in patients showing inadequate response to opioids. According to the Neuropathic Pain Special Interest Group, tramadol and opioids are the first line of treatment for cancer-related neuropathic pain. Lidocaine, oxcarbazepine, topiramate, lamotrigine, mexiletine, corticosteroids, baclofen and clonazepam are other common agents.

The World Health Organization suggests nonopiods as the first of three crucial steps in cancer pain management.

NSAIDs are associated with hepatic and renal risk; therefore FDA has advocated in 2011 that acetaminophen amount in a product should not be more than 325 mg per dosage unit.

It was concluded that with appropriate education and tools, cancer pain can be effectively managed. Adequate training and proper knowledge are extremely important for providing proper treatment.

Reference:

Chronic Tumor-Related Pain; Tran et al; US Pharm. 2012;37(5):HS-9-HS-12

Source-Medindia