should facilitate rapid progress of research in this area. Subjective reports of patients about quality of life and symptoms are increasingly accepted as reasonable measures for clinical and laboratory research. Quality-of-life outcomes—including aspects of symptom control—have become more accepted as clinical trial end points. New technologies offer unique opportunities to understand the nature, mechanisms, and expression of symptoms that were not possible a few years ago (e.g., new brain imaging techniques to study pain and depression) and, further, to see how treatment affects them. Developments in neurobiology have opened windows to a better understanding of end-of-life symptoms. Exciting new agents that could provide better control of most of the symptoms of the dying process have been and are being developed. There is a real possibility that individual variation in symptom expression may be better understood through progress in genetic science. It can no longer be said that tools to advance the area are lacking, and there is also no lack of research targets.

The understanding of pain, although more advanced than that of other symptoms, still has enormous gaps to be filled. This finding is confirmed and detailed in a January 2001 AHRQ Evidence Report/Technology Assessment, Management of Cancer Pain (AHRQ, 2001), which concludes:

Randomized controlled trials establish that many current treatment modalities can individually reduce cancer pain. These trials constitute 1 percent of the published literature on cancer pain, enroll one in 10,000 patients at risk for cancer pain in industrialized countries, are often heterogeneous, and use poor methodology. Leading investigators in the area of cancer pain relief have repeatedly called for improving the quality of trials in this area. The quantity and quality of scientific evidence on cancer pain relief still, however, compare unfavorably with the great deal that is known about other high-impact conditions, including cancer itself. In the current era of patient-centered care, closing this gap should be a high research priority.

Our understanding of symptoms other than pain is much more limited. Research examining ways of improving the care given to patients with advanced cancer is just beginning. Methods for studying and providing for the more complex subjective needs of patients (spiritual, existential) have to be developed. Few of the common practices of caring for patients with advanced cancer have been subjected to careful randomized clinical trials, impeding the provision of evidence-based practice recommendations.

Cleeland has laid out a research agenda for the most important symptoms in the disciplines of basic science, epidemiology, social-behavioral research, health services research, and clinical trials. Specific opportunities and currently unmet research needs in symptom control are outlined in Table 1-3.

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