The prevalence of pain among cancer patients varies depending on which studies you reference, but it's often reported that up to 90% of cancer patients experience pain [1]. Particularly concerning is that the severity of pain is typically high, especially in the later stages of cancer. When you consider that around 50% of cancer patients do not receive adequate pain management, it's clear that current approaches need re-evaluation [1].
The World Health Organization (WHO) analgesic ladder has played a significant role in improving cancer pain control. It's a simple concept, easy to understand and apply, and has been widely adopted. However, despite its benefits, it still falls short in many cases. More recently, experts in pain medicine and palliative care have started questioning whether the WHO ladder is still the best approach [2].
One of the major strengths of the WHO ladder—its simplicity—is also a key limitation. It offers a single-dimensional solution to a complex, multi-faceted problem. Additionally, societal changes and the growing reliance on opioids means that the primary medication used in the WHO ladder—opioids—requires stricter regulation and better management.
In light of these concerns, it's clear that managing cancer pain requires more than just opioids.
This blog aims to explore why a broader approach is necessary, focusing on the limitations of the opioid-centric model and the need for alternative pain management strategies.
Although opioids can be effective in the right context and with the right patients, their risks and potential side effects cannot be ignored. They can also be used to treat other symptoms associated with cancer, like dyspnea, but their use must be carefully managed.
Overall, the management of cancer pain demands a multi-modal and multidisciplinary approach, recognising that opioids are just one piece of a much larger puzzle [1].
1. Neuropathic pain
Neuropathic pain is a common issue in the cancer population, and opioids aren't effective for treating it. There are many potential causes for this type of pain in cancer patients:
Tumour growth
As a tumour grows, it can cause pain by compressing surrounding structures.
Cancer treatments
Chemotherapy, radiation, and aggressive surgeries can all lead to pain, sometimes with severe complications. For example, invasive surgeries like thoracotomy have an incidence of severe, persistent post-surgical pain of at least 10% [3]. Chemotherapy-induced peripheral neuropathy, often caused by specific agents, can have an incidence as high as 90% during the immediate post-treatment phase.
Overall, the prevalence of neuropathic pain in cancer patients is around 20%, but it can rise to 40% in cases where there's a mix of nociceptive and neuropathic pain [4]. Even cancer survivors often continue to experience neuropathic pain, with a reported prevalence of 40% [5].
This wouldn't be a significant issue if opioids were effective against neuropathic pain, but they aren't. Neuropathic pain is notoriously hard to manage, and many of the medications used to treat it come with extensive side effects. The same applies to opioids, which have their own set of complications and limited effectiveness. A recent Cochrane review stated that there's no clear evidence that opioids are better than placebo for neuropathic pain over the long term [6].
Additionally, guidelines from the NeuPSIG (special interest group on neuropathic pain) based on meta-analysis published in the Lancet, provide only a "weak recommendation" for the use of strong opioids, suggesting they be considered only as a third-line option.
Given these factors, it's clear that an approach focusing on escalating opioid dosages will not be effective for many cancer patients with neuropathic pain. Instead, a more comprehensive pain management strategy is needed, taking into account the limitations and risks associated with opioid use.
2. Opioids can worsen the pain
Opioid-Induced Hyperalgesia (OIH) is a complex condition where long-term use of opioids leads to an exaggerated response to pain. This is a significant concern in cancer pain management, where opioids are often used to control severe discomfort.
What Is Opioid-Induced Hyperalgesia (OIH)?
OIH occurs when chronic opioid use results in a heightened sensitivity to pain, creating a paradoxical effect. Instead of reducing pain, increased opioid doses can lead to greater pain perception. This condition is often observed in opioid-dependent individuals and even in patients undergoing anaesthesia.
The Paradox of OIH
As opioid doses are increased to manage pain, OIH can become more pronounced, causing a spiralling effect where the more opioids are used, the greater the pain sensitivity. The underlying mechanisms of OIH are not fully understood, but researchers believe non-opioid receptors like glycine and NMDA play a role in this process.
Side Effects and Tolerance
Opioids come with a range of side effects, including constipation, nausea, vomiting, and pupil constriction (miosis). Medical students are taught about opioid tolerance, where continuous use requires higher doses for the same effect. This tolerance can further exacerbate the issue, leading to more intense opioid use and potentially worsening pain.
How OIH Affects Cancer Pain Management
In cancer pain management, the challenge with OIH is that it can complicate the use of opioids. If patients experience heightened pain despite increasing opioid doses, it's critical to consider the possibility of OIH. This condition underscores the need for a balanced approach to pain management that includes non-opioid strategies.
Seeking Alternatives to Manage Cancer Pain
Given the risks associated with OIH, pain management strategies should focus on multimodal approaches, integrating various therapies to manage pain without solely relying on opioids. This might include non-opioid medications, interventional pain management techniques, physical therapy, and psychological support.
3. The Role of Interventional Pain Management in Treating Cancer Pain
Interventional pain management is often an underutilised approach in cancer pain treatment. There are several reasons for this, but accessibility is likely the biggest factor. However, a variety of interventional techniques are available, and when applied correctly, they can be highly effective in managing cancer pain. The choice of intervention depends on various factors, including the type of tumour, the underlying cause of the pain, the stage of the disease, and the severity of the pain. Some procedures are only suitable for patients with limited prognosis, while others can be used throughout a patient's journey with cancer.
Key Interventional Pain Management Techniques
Here are some examples of interventional pain management techniques that can be used to treat cancer-related pain:
Most nerves and their pain signals can be blocked using local anaesthesia or a heat ablation or an alcohol neurolysis. e.g. a coeliac plexus is targeted to manage pain originating from upper abdominal cancers. It is performed by pain specialists and interventional radiologists. The coeliac plexus block can be especially useful for patients with poorly controlled pain and a limited prognosis. When done correctly, this block can offer significant pain relief with minimal side effects.
Neuromodulation
This broad category encompasses two primary approaches: intrathecal drug delivery and spinal cord stimulation. Neuromodulation involves delivering pain-relief medication or stimulating specific nerves to manage pain.
Intrathecal Pain Management
This technique involves administering pain medications directly into the intrathecal space, which is located near the spinal cord. The benefit of this approach is that it requires a lower dose to achieve pain relief, reducing the potential for side effects.
Spinal Cord Stimulation
This technology has come a long way since its early days. It can be particularly effective in treating cancer pain, especially when other treatments have not provided sufficient relief. It's also useful for addressing persistent neuropathic pain in cancer survivors.
These interventional techniques offer promising alternatives to traditional pain management methods, like opioid-based therapies. The key to success with interventional pain management is proper patient selection and ensuring the procedure is done by experienced professionals. If you're experiencing cancer-related pain and have not found relief with conventional treatments, consult a pain management specialist to explore these interventional options.
4. The Psychosocial Aspects
A critical yet often overlooked aspect of cancer care is the psychosocial well-being of patients. Cancer can have a significant emotional impact, and this varies at different stages of the patient's journey. While a deeper discussion on the various psychosocial interventions would require a dedicated blog, it is clear that the psychological health of cancer patients plays a pivotal role in their overall treatment and recovery.
A recent meta-analysis showed that psychosocial interventions can have a moderate effect in reducing pain severity, reinforcing the importance of addressing emotional and mental health as part of cancer pain management. Having a dedicated cancer pain psychologist as part of the care team can help both the patient and their family cope with the stress and uncertainty that often accompanies cancer diagnosis and treatment.
Integrating psychosocial support into the broader treatment plan is essential to provide comprehensive care for those affected by cancer. Whether it's through therapy, support groups, or stress-reduction techniques, these interventions can significantly enhance the quality of life for cancer patients.
5. A team approach is required
Pain specialists play a critical role in supporting cancer pain teams by bringing their advanced expertise in pain management to the multidisciplinary care of cancer patients. They work collaboratively with oncologists, palliative care professionals, nurses, and other healthcare providers to develop comprehensive pain management strategies tailored to individual patient needs.
Pain specialists are skilled in a wide array of techniques, including medication management, interventional procedures, and neuromodulation, which can be crucial for addressing complex pain scenarios often seen in cancer patients.
By conducting thorough pain assessments, pain specialists help identify the underlying causes of pain, whether they stem from the cancer itself, its treatment, or other co-existing conditions. Their input allows the team to create personalised pain management plans that not only aim to alleviate pain but also improve the patient's overall quality of life. In doing so, pain specialists contribute significantly to the holistic approach that is essential in cancer care, providing both immediate relief and long-term support for patients navigating the challenges of cancer and its treatment.
SUMMARY
Whilst opioids have a pivotal role in managing cancer pain, they aren't a treat-all-pain solution, particularly given the complex and varied nature of cancer-related pain.
Despite their versatility, relying solely on opioids for cancer pain management is not the best approach, as the evidence for their effectiveness in certain scenarios is limited, and other treatment methods can be just as beneficial.
To ensure optimal care, opioids should be one part of a broader, multi-modal, and multidisciplinary pain management strategy. This comprehensive approach can better address the various types of pain experienced by cancer patients, ensuring they receive the best possible treatment.
More information on cancer pain can be found here.
