Abstract: Objective To explore the relationship between the types of female breast density and age and breast cancer.Methods By accepting the digital mammography X-ray examination for 5006 women cases and according to the ACR BI-RADS standard in the fourth edition,the breast density assessment was quantified.We analysed the relationship between the breast density and age and breast cancer.Results In 5006 cases,the average female age was between 44.22±8.09 years old,median age was 43 years old.The components of the breast density were fat type,small amount type,large amount type and compact type each count were 256(5.11%),726(14.51%),3719(74.29%),305(6.09%)respectively.By dividing into different age-group to analyze the breast density,there was significant statistical differences of the breast density among age-groups(P＜0.001).Among them the breast cancer were 184 cases.Age was between 51.26±10.15 years old.Breast cancer in each breast density were fat type 10.16%(26/256),small amount type 9.09%(66/726),large amount type 2.45%(91/3719)and compact type 0.33%(1/305).There were statistical differences among age-groups and breast densities and breast(P＜0.001).Conclusion Age plays a very important effects on the female breast density.The lower breast density is a high risk factor to breast cancer occurrence.

Key words: Breast density, Mammography, Breast cancer, BI-RADS