Cancer pain management: What should be done to improve effectiveness?

In 2008, the International Agency for Research on Cancer (1) estimated that there were more than 12.4 million new cancer cases worldwide, 7.6 million deaths from the disease, and 28 million people with cancer surviving five years after initial diagnosis. Advances in cancer treatment have increased survival rates and prolonged life spans (2), but there is still inevitable damage to healthy cells and tissues due either to the cancer itself or to the therapy applied, and side effects or symptoms therefore occur during or after the treatment. Among the various symptoms experienced by cancer patients, pain is one of the most prevalent (3).

Defined as 'unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage' (4), pain is one of the most distressful symptoms suffered by cancer patients (5,6), and can occur at various times throughout the cancer trajectory. Unrelieved pain greatly affects patients' daily living activities, emotions and quality of life (7,8). A comprehensive pain assessment and the ready availability of effective therapies are essential for relieving cancer pain.

In this issue of The Annals of Palliative Medicine, Situ et al. (9) use another lens to examine present evidence on the assessment and management of cancer pain. Their paper provides an overview of developments in cancer pain classification and assessment, as well as considering the effectiveness of various treatments. While the classification and assessment of pain together form a crucial step in optimal pain management, the findings of this review show a lack of comprehensive validation in existing classifications and assessments. Although various tools have been developed, there is no universal accepted tool for pain assessment in palliative care settings. Another problem identified in the review is the applicability of pain assessment tools to both research and clinical practice. While a comprehensive, multi-dimensional and systematic pain assessment is essential, it may increase the burden of clinicians and patients and, in turn, decrease compliance and application rates. Developing and validating a standardised cancer pain classification and practical assessment system through international collaboration seems to be the best way forward, and Situ et al.'s review (9) provides important insights into gaps that need to be addressed by future research.

The most widely accepted algorithm for the treatment of cancer pain was developed by the World Health Organisation (WHO) (10). It suggests that patients with pain be started (in the following order) on nonopioids such as paracetamol or a non-steroidal anti-inflammatory drug (NSAID), then a 'mild opioid' such as codeine, and then a 'strong opioid' such as morphine, until the patient's pain is relieved. According to the WHO report, this algorithm is 80-90% effective provided that patients receive the right drug in the right dose at the right time (10).

While opioid-based pharmaceutical therapy is still the main method of cancer pain management, the use of other non-opioid pharmaceutical therapies or non-pharmaceutical methods such as adjuvant therapy has been proven effective (9). Various clinical guidelines also provide for different types of therapy (11,12). However, the Situ et al. (9) paper presents additional evidence concerning alternative treatments commonly used in Chinese culture: acupuncture, massage and Chinese herbal medicine. It is likely that a combination of both Western and Eastern approaches to cancer pain management will prove to be necessary. However, further research is needed to examine the effectiveness of this dual approach.

Pain is a subjective experience which is too complex to deal with through a single algorithm. More international collaboration is needed to develop a universal and practical tool for pain assessment in the palliative care setting, and more research should be conducted to evaluate the effectiveness of a combined Western and Eastern therapy - always bearing in mind, of course, that clinicians must ensure the needs of the individual patient are addressed in any implementation of cancer pain management.

Footnote

No potential conflict of interest.

References

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