Dispositional optimism and therapeutic expectations in early-phase oncology trials

BACKGROUND Prior research has identified unrealistic optimism as a bias that might impair informed consent among patient-subjects in early-phase oncology trials. However, optimism is not a unitary construct; it also can be defined as a general disposition, or what is called dispositional optimism. The authors assessed whether dispositional optimism would be related to high expectations for personal therapeutic benefit reported by patient-subjects in these trials but not to the therapeutic misconception. The authors also assessed how dispositional optimism related to unrealistic optimism. METHODS Patient-subjects completed questionnaires designed to measure expectations for therapeutic benefit, dispositional optimism, unrealistic optimism, and the therapeutic misconception. RESULTS Dispositional optimism was found to be significantly associated with higher expectations for personal therapeutic benefit (Spearman rank correlation coefficient [r], 0.333; P<.0001), but was not associated with the therapeutic misconception (Spearman r, -0.075; P =.329). Dispositional optimism was found to be weakly associated with unrealistic optimism (Spearman r, 0.215; P =.005). On multivariate analysis, both dispositional optimism (P =.02) and unrealistic optimism (P<.0001) were found to be independently associated with high expectations for personal therapeutic benefit. Unrealistic optimism (P =.0001), but not dispositional optimism, was found to be independently associated with the therapeutic misconception. CONCLUSIONS High expectations for therapeutic benefit among patient-subjects in early-phase oncology trials should not be assumed to result from misunderstanding of specific information regarding the trials. The data from the current study indicate that these expectations are associated with either a dispositionally positive outlook on life or biased expectations concerning specific aspects of trial participation. Not all manifestations of optimism are the same, and different types of optimism likely have different consequences for informed consent in early-phase oncology research. Cancer 2016;122:1238-46.