The impact of personality on the risk and survival of breast cancer: a Mendelian randomization analysis

It has long been hypothesized that personality plays a causative role in incidence and outcome of breast cancer (BC), but epidemiological evidence of association between personality and BC is inconsistent.We used two-sample Mendelian randomization analysis to estimate the impact of personality on the risk and survival of BC. In total, 109 single nucleotide polymorphisms (SNPs) were utilized as instruments of neuroticism from a large-scale Genome-Wide Association Studies (GWAS), and five SNPs were utilized as instruments of extraversion from Genetic of Personality Consortium and 23andMe. Genetic association with the risk and survival of overall and individual subtype BC were obtained from the Breast Cancer Association Consortium.Neuroticism is significantly associated with the risk of overall BC [odds ratio (OR) 1.06; 95% confidence interval (CI) 1.01-1.11; p = 0.015] and the risk of luminal A BC (OR 1.09; 95% CI 1.03-1.16; p = 0.004). Extraversion is not associated with the risk of BC. None of neuroticism or extraversion is associated with the survival of BC.Neuroticism was associated with a modest increased risk of BC and particularly luminal A BC.