Bullying in adolescents: role, type of violence and determinants.

Objective: To determine the prevalence of bullying and its determinants among adolescents attending school.

Method: An analytical cross-sectional study was conducted with a sample of adolescents, who were selected using a multistage probability sampling, from 20 public educational institutions in a Colombian city, in which a simple and multivariate binomial regression was carried out.

Results: A total of 500 adolescents participated from which 50.

[Physical activity and breast cancer risk in Mexican women].

Objective: To evaluate the effect of moderate physical activity (hours per week and METs hours per week) on the risk of breast cancer (BC) in Mexican women.

Material And Methods: This is the initial stage of a case control multicentric study based in the Federal District, Monterrey and Veracruz, Mexico, during 2004. Fifty eight cases paired to 58 control cases on quinquennium of age, and belonging to the health system were analyzed: three hospitals from the IMSS, three from ISSSTE and three from SS participated.