Dr Reshad Mirnour, Specialist Pain Medicine Physician, Ardross
Pain is a prevalent and significant concern in cancer patients, warranting careful attention and management. Pain can happen at any stage of the disease and like any other pain condition, a socio-psycho-biomedical approach needs to be considered.
A multidisciplinary setting is often necessary, involving the patient’s general practitioner, pain specialist, palliative care physician, radiation oncologist, surgeon and allied health.
In patients with cancer, pain may arise directly from the disease itself, such as the mass effect of a tumour, or indirectly as a consequence of cancer, for example pathological fractures, or its treatment, such as chemotherapy-induced peripheral neuropathy.
Perhaps the first step of pain assessment in cancer is to determine the prognosis which can significantly influence the management. Cancer is a life-changing diagnosis, and therefore, psychological and environmental pain contributors should be carefully explored and managed as well as any biomedical factors.
Addressing patients’ immediate and long-term psychological, social and existential needs is a crucial part of holistic pain management.
Pharmacotherapy should include multimodal analgesia including opioids, non-opioid analgesics and anti-neuropathic agents. Although opioids are no longer recommended for chronic non-cancer pain, they are one of the most frequently used medications in cancer pain, as well as the most effective ones.
Morphine, an old opioid, and codeine are two medications that are recommended in the WHO guideline for cancer pain treatment (the WHO analgesics ladder). However, there are many other opioids with different mechanisms and routes of administration which include oral, rectal, sublingual, transdermal and injectables – intravenous, or subcutaneous – and intrathecal.
The oral route is the most common method of delivering opioids to cancer patients as it is less invasive and, therefore the most preferable. The transdermal route is suitable particularly for longer-term pain relief and in situations when the use of oral medication is not possible.
The new generation of opioids such as tapentadol and buprenorphine are considered safer options than conventional opioids, particularly with a longer survival when the opioids are considered for a longer period.
However, caution should be practised when opioids are prescribed in patients with cured cancer as the ongoing chronic pain may no longer be considered cancer pain. In such cases, or when long-term remission is expected, an appropriate weaning plan is necessary
Apart from the quality of life, pain and related stress can promote the progression of cancer.
Based on the current evidence, 19 out of 20 patients treated with opioids for their cancer pain report their moderate to severe pain is reduced to mild or no pain. Interestingly, only one in 10 people treated with these medications have to change or stop them due to side effects.
The side effects include nausea, vomiting, opioid-induced ventilatory impairment, cognitive impairment, opioid-induced hyperalgesia, constipation, drowsiness, itching, tolerance, dependency and addiction.
Although opioids are the most effective medications, neuropathic pain is usually resistant to opioids and other medicines are often prescribed for its management.
There is a general concern about the effect of opioids on the progression of cancer. This is a controversial subject and while some animal studies show opioids can enhance the progression of cancer, others show an improved overall survival following treatment with opioids, probably due to improved compliance with cancer treatment and better quality of life.
Generally, we need more research in this area to have a better understanding of the role of opioids on cancer outcomes.
Key messages
- Holistic care is key: Cancer pain needs a multidisciplinary approach addressing medical, psychosocial, and existential factors.
- Opioids need caution: Effective for cancer pain but require careful use in long-term survivors.
- Multiple pharmacological and non-pharmacological options are available to improve quality of life and possibly cancer survival
There are non-analgesic medications that can be used as part of pain management in cancer patients. Monoclonal antibodies have been used to treat bone pain from cancer metastasis and currently denosumab is PBS-subsidised for such indications in breast cancer.
In terms of non-pharmacological options, pain procedures can provide excellent pain relief while minimising the side effects of opioids.
Examples are coeliac plexus block or ablation, sympathetic ablation, intrathecal pumps, and peripheral nerve blocks. Moreover, radiotherapy can be an effective non-pharmacological strategy for bone pain.
In summary, cancer pain is a manageable issue that needs early intervention to improve patients’ quality of life and compliance with cancer treatment.
Multiple pharmacological and non-pharmacological strategies are available to manage this undertreated condition. The use of opioids in cancer survivors should be assessed in the same manner as in patients with chronic non-cancer pain.
Author competing interests – nil
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