A Cochrane review included ten studies with a total of 1709 subjects. Tamoxifen versus placebo/no intervention had no significant effect on overall survival (hazard ratio 1.05; 95% CI 0.94 to 1.16; p=0.4). Tamoxifen tended to increase mortality in trials with higher methodological quality, although this may have been confounded by the use of higher doses of tamoxifen in the better quality trials. Tamoxifen was associated with adverse effects.