When expectations predict experience: the influence of psychological factors on chemotherapy toxicities.

Context: Patients with cancer undergoing similar treatments experience variable severity and frequency of side effects not adequately explained by pharmacological mechanisms, suggesting psychological influence.

Objectives: First, this study aimed to further examine the relationship between patients' expectations of multiple chemotherapy-related toxicities and experiences. Second, this study aimed to explore the impact of anxiety and cancer coping styles to aid in informing interventions to lessen such expectations.

Methods: A total of 59 eligible, consenting patients with cancer rated their expectations of 20 chemotherapy toxicities on 100-point linear analogue self-assessment indicators before treatment and completed the Spielberger State Anxiety Inventory and the Mental Adjustment to Cancer scale. Patients then rated their experience of side effects after one chemotherapy session.

Results: Regressions controlling primary treating nurse influence and patient performance status showed toxicity experience was significantly predicted by patient expectations of mood changes, bleeding, skin itchiness, hair loss, feeling tired, and sleep disturbance (β=0.30-0.55). Anxiety was significantly related to expectations of nervousness and mood changes; the coping style Fighting Spirit showed no significant associations, whereas conversely, Anxious Preoccupation showed some degree of association with all 20 toxicities (r=0.11-0.34).

Conclusion: Findings support the growing contention that patient expectations influence experience, negatively impacting quality of life. As it is unethical to withhold treatment information, research into screening for at-risk patients and offering brief interventions to minimize Anxious Preoccupation could be one way to reduce overall side effect burden, perhaps in the case of many medical interventions.