Pre-infusion expectations predict post-treatment nausea during repeated adjuvant chemotherapy infusions for breast cancer

Objectives. To examine the relations between expectations of post-treatment nausea (PTN) and experience of post-treatment nausea beginning at the first infusion and continuing across a series of subsequent infusions in order to assess the influence of patients' expectations on a non-volitional outcome in a clinical setting. Design. The study utilized a prospective, longitudinal design to capture the development of relations between expectations and experiences of post-treatment nausea. Methods. Fifty-two women with breast cancer scheduled to receive standard outpatient adjuvant chemotherapy were studied. Study questionnaires included measures of chemotherapy-related side effects, patient expectations, emotional distress and mood disturbance. Results. Significant relations between expectations and incidence of post-treatment nausea at Infusions 2-7 were found (P < .05). To explore the possibility that expectations were simply based on patients' most recent experience of post-treatment nausea, we statistically controlled for that experience. Expectations of post-treatment nausea made a unique contribution to the prediction of post-treatment nausea at Infusions 4-7 (p < .05) in that analysis. No support was found for the possibility that the relations between expectations and post-treatment nausea were due to patients' emotional distress at the time of the assessments. Conclusions. These results provide the first indication in the literature that the influence of expectations on post-treatment nausea changes as patients gain experience with chemotherapy.