Abstract
Meta-analysis is a widely used tool to synthesize the results of a set of primary studies leading to more powerful conclusions than those provided by isolated ones. To evaluate the effect of allocated radiotherapy, types of breast surgery and other risk factors over death risk in early breast cancer patients, we carried out a meta-analysis using logistic regression attending to the dichotomous character of the outcome.Our findings suggest that the type of breast surgery is an effect modifier of the risk factors over death in early breast cancer patients. The effect of allocated radiotherapy is associated with a less risk of death only for patients who had mastectomy plus axillary sampling. The effect of a systemic treatment is not associated with death risk for patients who had breast conservation, on the contrary it is associated for those patients with mastectomy alone and with mastectomy with axillary clearance.