Personality traits and cancer risk and survival based on Finnish and Swedish registry data.

Personality traits have been studied extensively as risk and prognostic factors for cancer; however, the association remains unclear. This prospective, population-based cohort study comprised 59,548 Swedish (1974-1999) and Finnish (1976-2004) participants who completed a questionnaire eliciting information for the Eysenck Personality Inventory and on health behavior at baseline. To analyze the association of personality traits extraversion and neuroticism with risk of cancer, the authors identified 4,631 cancer cases for a maximum 30 years of follow-up. To assess the association with cancer survival among the Finnish participants, they identified 2,733 cancer cases and, later, 1,548 deaths for a maximum 29 years of follow-up. Hazard ratios were estimated by treating the personality scales as continuous variables and are presented per one increase in score on each scale. In multivariate analyses, extraversion and neuroticism were not significantly associated with risk of cancers at all sites (extraversion: hazard ratio = 0.99, 95% confidence interval: 0.98, 1.01; neuroticism: hazard ratio = 1.00, 95% confidence interval: 0.99, 1.02). Results showed no significant association between these traits and the hazard ratio for death after cancers at all sites, and they do not support the hypothesis that extraversion and neuroticism are direct risk factors for cancer or survival after cancer.