Illness perceptions within 6 months of cancer diagnosis are an independent prospective predictor of health-related quality of life 15 months post-diagnosis

Objective: Studies have found that illness perceptions explain significant variance in health outcomes in numerous diseases. However, most of the research is cross-sectional and non-oncological. We examined, for the first time in breast, colorectal and prostate cancer patients, if cognitive and emotional illness perceptions near diagnosis predict future multidimensional health-related quality of life (HRQoL). Methods: UK-based patients (N = 334) completed the illness perception questionnaire-revised within 6 months post-diagnosis and the quality of life in adult cancer survivors scale 15 months post-diagnosis. Sociodemographic and clinical data were obtained from medical records. Hierarchical multiple regression analyses were conducted. Results: The sociodemographic and clinical factors collectively significantly predicted 8/12 HRQoL domains, although for 5/8 accounted for <10% of the variance. For all 12 HRQoL domains, illness perceptions collectively explained significant substantial additional variance (∆R² range: 5.6–27.9%), and a single illness perception questionnaire-revised dimension was the best individual predictor of 9/12 HRQoL domains. The consequences dimension independently predicted 7/12 HRQoL domains; patients who believed their cancer would have a more serious negative impact on their life reported poorer future HRQoL. The emotional representations and identity dimensions also predicted multiple HRQoL domains. Conclusions: Future research should focus on realising the potential of illness perceptions as a modifiable target for and mediating mechanism of interventions to improve patients' HRQoL.