Birth control may increase chance of breast cancer by as much as 38%. The risk exists not only for older generations of hormonal contraceptives but also for the products that many women use today. Study used an average of 10 years of data from more than 1.8 million Danish women.

See the source article by following the link below:
Birth control may increase chance of breast cancer by as much as 38%. The risk exists not only for older generations of hormonal contraceptives but also for the products that many women use today. Study used an average of 10 years of data from more than 1.8 million Danish women.