High neuroticism is associated with common late adverse effects in a nationwide sample of long-term breast cancer survivors

PURPOSE: Neuroticism is a basic personality trait characterized by negative emotions triggered by stress such as a breast cancer diagnosis and its treatment. Due to lack of relevant research, the purpose of this study was to examine if high neuroticism is associated with seven common late adverse effects (LAEs) in long-term (≥ 5 years) breast cancer survivors (BCSs). METHODS: All female Norwegian BCSs aged 20–65 years when diagnosed with stage I–III breast cancer in 2011 or 2012 were invited to a questionnaire study in 2019 (N = 2803), of whom 48% participated (N = 1355). Neuroticism was self-rated using the abridged version of the Eysenck Personality Questionnaire, and scores dichotomized into high and low neuroticism. LAEs were defined by categorization of ratings on the EORTC QLQ-C30 (cognitive function, pain, and sleep problems) and QLQ-BR23 (arm problems) questionnaires, and categorizations of scale scores on mental distress, fatigue, and neuropathy. Associations between high neuroticism and LAEs were explored using multivariate logistic regression analyses. RESULTS: High neuroticism was found in 40% (95%CI 37–42%) of BCSs. All LAEs were significantly more common among BCSs with high compared to low neuroticism. In multivariable analyses, high neuroticism was positively associated with all LAEs except neuropathy. Systemic treatment, somatic comorbidity, and not being in paid work were also significantly associated with all LAEs. CONCLUSIONS: High neuroticism is prevalent and associated with increased risks of LAEs among BCSs. Identification of high neuroticism could improve the follow-up care of BCSs as effective interventions for the condition exist. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s10549-023-07055-2.