Background. Jacobs and Bovasso reported (Psychological Medicine 2000, 30, 669–678) that maternal death in childhood and chronic severe depression in adulthood were associated with subsequent breast cancer. We have examined the effects of parental loss in childhood and psychiatric disorder in adult life on breast cancer risk using a national birth cohort study.

Method. Eighty-three cases of breast cancer were diagnosed in a study of 2253 women followed from birth to age 59 years. Cox proportional hazards models were used to test whether breast cancer rates were higher in women who experienced parental death and divorce before age 16, psychiatric disorders between 15 and 32 years, symptoms of anxiety and depression at 36 years, or use of antidepressant medication at 31 or 36 years than in women who did not have these experiences.

Results. There was no overall association between parental death, parental divorce or psychiatric disorder and the incidence of breast cancer. There was some evidence that women with more severe psychiatric disorders between the ages of 15 and 32 years were more likely to develop breast cancer early. The interaction between parental divorce and severe psychiatric disorder was non-significant (p=0·1); however, the group who experienced both these events had an increased breast cancer risk compared with those who experienced neither [hazard ratio (HR) 2·64, 95% confidence interval (CI) 1·13–6·19].

Conclusions. Our study does not provide strong support for the hypothesis that early loss or adult psychiatric disorders are associated with breast cancer. A meta-analysis is needed that uses data from all available cohort studies and investigates possible interactive effects on breast cancer risk.