As noted in the previous papers in this issue of Seminars in Oncology Nursing, a variety of biomarkers are used in risk appraisal, early detection, diagnosis, and management of cancer. Some of these biomarkers have been available for decades. In contrast, the use of biomarkers to evaluate symptoms and quality of life (QOL) of in patients undergoing cancer treatment and in cancer survivors is a relatively new field of scientific inquiry.1-3
Delays in the development of biomarkers for the assessment of cancer symptoms and for the evaluation of the impact of cancer and its treatments on various aspects of QOL may be attributed to a number of factors. First, symptoms and QOL outcomes are subjective phenomenon. Initial efforts to assess these phenomena were focused on the development and testing of valid and reliable instruments to evaluate these important patient-reported outcomes. Second, symptom management and QOL researchers, for the most part, worked in a relative vacuum and lacked expertise in the development and testing of biomarkers based on molecular mechanisms. However, as the underlying mechanisms for the most common symptoms experienced by cancer patients and survivors (i.e., pain,4
) are being elucidated through studies in both animals and humans, the need to identify clinically relevant biomarkers for individual symptoms and symptom clusters,13-15
as well as QOL outcomes has become a scientific imperative.
The development of sensitive and specific biomarkers, that correlate with subjective reports of symptoms and QOL, could be used to identify patients at greatest risk for more severe symptoms and poorer QOL outcomes. In addition, as with treatments for cancer, sensitive and specific biomarkers could be used to monitor the efficacy of symptom management and QOL of life interventions, as well as the side effects associated with these interventions. This convergence of subjective and objective measures could lead to the development of personalized symptom management strategies prior to the initiation of cancer therapy that might prevent the development of chronic symptoms, as well as decrements in functional status and poorer QOL outcomes particularly in cancer survivors.
The development of specific biomarkers for the most common symptoms associated with cancer and its treatments, as well as biomarkers of treatment efficacy is still in its infancy but initial efforts are promising. The purpose of this paper is to review the evidence on a number of biomarkers that show potential clinical utility in the prediction of and treatment responsiveness for the four most common symptoms associated with cancer and its treatment and that persist in cancer survivors, namely pain, fatigue, sleep disturbance, and depression. When research findings from patients with cancer are not available, data are provided on the sensitivity and specificity of the various biomarkers from other populations. This paper concludes with a discussion of the clinical implications for these biomarkers and recommendations for future research.