Quantity, design, and scope of the palliative oncology literature.

The current state of the palliative oncology literature is unclear. We examined and compared the quantity, research design, and research topics of palliative oncology publications in the first 6 months of 2004 with the first 6 months of 2009. We systematically searched MEDLINE, PsychInfo, EMBASE, ISI Web of Science, and CINAHL for original studies, review articles, and systematic reviews related to "palliative care" and "cancer" during the first 6 months of 2004 and 2009. Two physicians reviewed the literature independently and coded the study characteristics with high inter-rater reliability. We found a consistent decrease in the proportion of oncology studies related to palliative care between 2004 and 2009, despite an absolute increase in the total number of palliative oncology studies. Combining the two time periods, the most common original study designs were case report/series, cross-sectional studies, and qualitative studies. Randomized controlled trials comprised 6% of all original studies. The most common topics were physical symptoms, health services research, and psychosocial issues. Communication, decision making, spirituality, education, and research methodologies all represented <5% of the literature. Comparing 2004 with 2009, we found an increase in the proportion of original studies among all palliative oncology publications but no significant difference in study design or research topic. We identified significant deficiencies in the quantity, design, and scope of the palliative oncology literature. Further effort and resources are necessary to improve the evidence base for this important field.