Challenges in interpreting cytokine biomarkers in biobehavioral research: A breast cancer exemplar

Purpose: This report extends the findings of a prior study comparing the level of plasma cytokines in women with breast cancer to those of women with a benign breast biopsy with the addition of a normal comparison group. The results of this three-group comparison are presented as background for discussing several methodologic challenges for biobehavioral research in inflammatory-based conditions. Method: This study used a descriptive, cross-sectional design to compare the levels of plasma cytokines in women with breast cancer, women with a benign breast biopsy, and a normal comparison group. The levels of 17 cytokines were measured using multiplex bead array assays (Bio-Plex®). Data analysis included a variety of descriptive and graphical techniques to illustrate between-group differences in cytokine profiles. Results: The levels of plasma cytokines in the sample of 35 women who had recently been diagnosed with breast cancer, 24 women with a suspicious breast mass, who subsequently were found to have a benign breast biopsy, and 33 women in a normal comparison group present a background for discussing the implications of extreme between-group differences for biobehavioral nursing research. Both the levels of individual cytokines and their patterns were distinctly different in the three groups. Conclusion: The exemplar presented from the three-group comparison has implications for planning biobehavioral nursing research in patients with conditions characterized by inflammation.