Chemotherapeutic toxicity--the relationship between patients' pretreatment expectations and posttreatment results.

Patients receiving the same cancer chemotherapy regimens exhibit a highly variable incidence of toxic side effects. We studied 56 patients about to receive chemotherapy for the first time to determine whether their expectations of individual side effects were associated with the frequency and severity of the toxicity that they subsequently experienced. Patients completed a self-report questionnaire containing a list of 16 potential toxicities, asking them to indicate how certain they were of experiencing or not experiencing each. Prior to their third treatment, patients again completed a self-report scale indicating the incidence and severity of each side effect experienced. The frequency of actual side effects was much greater than patients anticipated. The most commonly reported side effects were tiredness, changes in appetite or taste, nervousness, and nausea. Patients' expectations failed to predict the occurrence or severity of the experience of common side effects. Anxiety levels and meaning attributed to side effects also were not associated with side effects experienced. Although psychological factors may play a role, it is likely that unique physiologic parameters account primarily for the variable and unpredictable relationship between chemotherapeutic agents and the side effects they induce.