Background. Belief that depression and other psychological factors predict breast cancer is common, but there have been few prospective epidemiological studies on this relationship.
Method. The relationship between depression, personality traits, illness attitudes, life events and health history, and breast cancer risk was studied in a prospective, 6–9 year follow-up of a cohort study of 10892 Finnish women of 48–50 years of age at the baseline. Cancer cases were obtained from the Cancer Registry of Finland. Multivariate logistic regression analysis was performed controlling for socioeconomic factors, family history of cancer, parity, and health behaviours.
Results. Breast cancer incidence in the cohort was 1·15 times the average in age group 50–59. There was no evidence of depression, trait anxiety, cynical distrust, or coping being significant predictors of breast cancer incidence.
Conclusion. In this cohort study with the 6–9 year follow-up, psychological factors such as depression, trait anxiety, cynical distrust, or coping did not increase breast cancer risk.