Introduction:

Breast cancer is most common among women; its risk factors have not been outlined from a broad approach of published reviews.

Objective:

To outline the risk factors of breast cancer from publications of case-control studies from 2008 to 2018.

Methods:

A systematic review of the literature based on the application of comprehensive and reproducible protocol, following identification, screening, selection and inclusion phases of PRISMA guide. Qualitative synthesis was performed with proportions and 95 % confidence intervals.

Results:

298 studies were analyzed in 2,927,342 women, mostly from Mexico (2 000 835). The countries with highest frequency of publication were USA. (20.9 %) and China (10.8 %). The most studied groups of risk factors were diet (26.6 %), reproductive factors (14.8 %) and lifestyle (9.1 %). The least studied are the biological ones. Only one approached this type of factor, reporting a strong association of IgG seroconversion in cytomegalovirus with the appearance of breast cancer. The three factors that registered the greatest strength of association were obesity, psychosocial factors and cytomegalovirus.

Conclusions:

We found a wide diversity of risk factors, some rigorous-design studies to establish solid etiological associations and others with initial research development or methodological problems that prevent consolidating causal hypotheses and therefore the possibility of intervening in the main triggers for the appearance of the disease.

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