Background: Many studies have shown an omission bias, but when the context is cancer, people seem to prefer active treatments to watchful waiting.
Objective: First, to investigate whether the preference for active treatment for cancer could depend on the associations attached to the inaction option, and second, to explore the kind of diagnosis that gives rise to the preference for action, by comparing scenarios differing in the status of the illness (already present v. could arise in the future), the kind of diagnosis (malign tumor, benign tumor, or nontumor), and the possible development of the tumor (growth v. degeneration).
Design: Between-subjects design with 8 hypothetical scenarios.
Participants: A total of 735 students participated in an Internet survey.
Measurements: Choice between watchful waiting and surgery, perceived severity of the diagnosis.
Results: Active treatment was preferred only when the scenario described watchful waiting as excluding surgery in the future. The critical aspect for participants' preference for active treatment was the malignancy of the tumor currently diagnosed. Perceived severity was also a significant predictor of treatment choice.
Limitations: Inability to infer causation in the relationship between choice and perceived severity.
Conclusions: Action is preferred to inaction when a malignant tumor is currently diagnosed and active treatments are not allowed in the future; under other conditions, participants prefer inaction (e.g., when active treatments are allowed in the future, or when the tumor is benign) or exhibit no preference (e.g., when it is not specified whether active treatments are allowed in the future).