The link between breast density and breast cancer risk is well established, however, this study introduced the association between breast density in young woman and reproductive/hormonal characteristics.

BACKGROUND: Although breast density is strongly associated with breast cancer there has not been much study into possible determinants of breast density in young women. Data from the Dietary Intervention Study in Children Follow-Up Study (DISC06) was used to investigate.

METHOD: Several questionnaires were completed by the women (aged 25-29) to assess demographic characteristics, medical, reproductive, and menstrual histories, medication use, and health habits, while non-contrast MRI was used to measure breast density.

RESULTS: The mean percent dense breast volume (%DBV) significantly decreased from 20.5% down to 16.0% for women who had given birth compared to women who had not. The age at which hormonal contraception was started also affected %DBV, which was 21.7% in women who started using hormones at 12-17 years old compared to 14.7% in women who were 22-28 years old when they started using hormones.

CONCLUSION: “Breast density in young women is inversely associated with parity and the age women started using hormonal contraceptives but positively associated with duration of hormone use.”