The role of patients' expectations in the development of anticipatory nausea related to chemotherapy for cancer.

Although anticipatory nausea (AN), which is reported by one-third of patients receiving chemotherapy for cancer, is thought to develop primarily by classical conditioning, response expectancies may also be important. The role of patients' expectations of nausea in the development of AN was examined in 63 female cancer patients receiving their first course of chemotherapy. Twenty women (32%) expected to experience nausea and twelve (19%) reported AN before the third cycle. Pretreatment expectations predicted AN at cycle three (Spearman's r = 0.41, P = 0.001). AN developed in 40% of patients who expected nausea, 13% of those who were uncertain whether they would develop it, and no patients who did not expect nausea. Logistic regression indicated that expecting nausea was the strongest predictor (chi(2) =13.15; P < 0.001). Results support a role for cognitive factors in the development of chemotherapy side effects and suggest testing psychologic interventions to modify patients' expectations.