Adverse life-events and risk of breast cancer: A meta-analysis

Objective. Studies examining the relationship between adverse life events a nd breast cancer have produced conflicting results. A systematic review of the published studies was therefore carried out. Methods. Electronic databases and bibliographies of review articles were se arched for studies in any language. Studies were assessed for methodologica l quality by two reviewers. Results. Twenty-nine studies were found. These were of variable quality. Ra ndom effects meta-analysis of the higher quality studies found no significa nt relationship between breast cancer and either bereavement (summary odds ratio (OK)=0.9; 95% confidence interval (CI) 0.57 to 1.45) or other adverse life-events (summary OR=0.8; 95% CI 0.61 to 1.06). Funnel plots may be sug gestive of publication bias, with small studies reporting negative findings less likely to be published. Conclusions. Good quality case-control studies, and the single large prospe ctive study in this area, do not support the hypothesis of a casual relatio nship between adverse life-events and onset of breast cancer.