ORIGINAL ARTICLE Open Access Distribution of dense breasts using screening mammography in Korean women: a retrospective observational study

OBJECTIVES: This retrospective observational study evaluated the distribution of dense breasts by age group among healthy Korean women. METHODS: Participants were women aged 30 years and older who voluntarily underwent screening mam-mography between January 2007 and December 2011. Women who received the Breast Imaging Reporting and Data System for mammographic density of 3 or 4 were defined as having dense breasts. The proportion of women with dense breasts (PDB, %) was calculated by dividing the number of participants with dense breasts by the total number of participants. RESULTS: Among the 231,058 women who participated, 78.15 % were classified as having dense breasts. PDB was highest in the youngest age group (PDB=94.87%) and lowest in the oldest age group. The greatest difference in PDB between adjacent age groups was observed in the group aged 60-64 years. CONCLUSIONS: The results show that the proportion of dense breasts by age group increased in all age groups, except in those aged 35-39 years. These findings suggest an association between the age distribution of dense breasts and trends in breast cancer incidence. Further studies are needed to estimate the change in breast can-cer incidence rate by age and the accumulation of fatty breast tissue in Korean women