Fatigue is the most common problem experienced by oncology patients.[1-2] In this issue of ONCOLOGY, Drs. Lesage and Portenoy present an excellent overview of the potential etiologies, assessment parameters, and treatment options for this complex, multidimensional symptom. As they note in their comprehensive review, research on this symptom, which has a significant impact on oncology patients’ ability to function and quality of life, is limited. Therefore, one is left to consider what important research questions need to be answered regarding cancer-related fatigue.
Because of the similarities between pain and fatigue (eg, both are subjective phenomena and multidimensional problems, with complex etiologies and multiple treatment options that need to be individualized), it may be beneficial to examine the conceptual ideas and research approaches that led to the greatest advances in our understanding of pain mechanisms and pain management and determine whether these ideas and approaches could be applied to investigations of cancer-related fatigue. It should be noted that some of the most important ideas and approaches regarding pain mechanisms and management evolved after years of research and clinical experience. Perhaps we can capitalize on the ones that enhanced our knowledge and apply them to more quickly improve the management of cancer-related fatigue.
One of the most revolutionary ideas in pain management to evolve in recent years is the concept that pain is more than a symptom. Pain is a disease and requires a disease management approach to ensure effective treatment. It took more than 30 years for this view to be fully appreciated, but it has become an accepted part of clinical practice through the establishment of medical departments of pain medicine and palliative care (such as the one that Dr. Portenoy chairs). Perhaps the same approach is warranted for fatigue. The recognition of fatigue as a disease could lead to more intensive investigations of this significant clinical problem.
Determining the Etiology
One of the cardinal principles of effective pain management is to ascertain the etiology or cause of the pain. For most pain management plans to be effective, they must focus on eliminating or ameliorating the cause of the pain. Although Drs. Lesage and Portenoy point out that there are likely to be multiple etiologies for cancer-related fatigue, the major priority of research is to identify the molecular and biochemical mechanisms that underlie its development. Clinicians often discount patients’ subjective reports of pain when a recognized etiology is not evident. Likewise, clinicians discount patients’ subjective reports of cancer-related fatigue because the underlying mechanisms are unknown.
Our understanding of the peripheral and central mechanisms that result in the development of acute and chronic pain was greatly enhanced when appropriate animal models were developed and used to evaluate the effects of mechanism-based interventions. Until scientists begin to collaborate with clinicians to develop animal models for cancer-related fatigue, progress in mechanistic-based interventions will be slow.