Abstract P5-01-03: Comparison of mammography findings between dense and non dense breast in Japanese subjects: The potential limitation of routine mammography

Abstract

Abstract Introduction Recently “Dense breast” has attracted numerous attention because of diagnostic difficulty in mammography among those harboring dense breast, which is far more frequent in Asian than Caucasian women. Therefore, in this study, we retrospectively evaluated the risks of subsequent development of malignancy through comparing the detailed mammographic characteristics between Japanese subjects harboring dense and non dense breasts. Methods We retrospectively examined mammorgraphic findings taken from March 2013 to March 2016 at Nahanishi Clinic, Okinawa, Japan. We stratified its density according to the suggestion of the Japan Central Organization on Quality Assurance of Breast Cancer Screening, which was defined by the proportion of fat area as follows; extremely high dense:10-20%, heterogeneously dense:40-50%, scattered fatty:70-90%, fatty: almost all the breast fat. “Dense breast” includes extremely high and heterogeneous dense. We evaluated the detailed radiological findings of each phenotypes including the characteristics of the mass, calcification and focal asymmetric density(FAD) and architectural distortion. We also compared the rates of subsequent cancer development and sensitivity of detecting cancer between those harboring dense and non dense breasts. Results We reviewed the mammography findings of 7747 Japanese women including 857 with breast cancers. When adjusted for age, the rate of dense breast was significantly associated with age, 88.6% in women in their 20s(vs40s p<0.001 OR3.402), with incremental decrease, 80.4% in 30s(P<0.001 OR1.802), 69.5% in 40s, 55.9% in 50s(P<0.001 OR0.512), 32.3% in 60s(P<0.001 OR 0.108), 19.5% in 70s(P<0.001 OR 0.106) and 5.3% in over 80s(P<0.001 OR0.024). The rate of malignancies was 9.1% (385) in dense and 13.6% (472) in non dense breasts. We then compared the mammographic findings between dense and non dense breast. Abnormal calcifications were detected more frequent(7.6%vs5.3% P<0.001 OR1.478) but masses less so(16.4%vs23.7% P<0.001 OR 0.632) in dense breast, while no significant differences detected in FADs(4.9%vs4.6% P=0.35 OR1.074) and distortions(1.2%vs1.4% P=0.29 OR=0.859) between dense and non dense breast. The rate of carcinoma was less frequent in dense breast among those associated with mammographic calcification(19%vs27.3% P<0.01 OR0.626) but more frequently in dense breast among those with masses (13%vs19% P<0.001 OR0.628). The rate of carcinoma was not different between dense and non dense breast in those with FADs (21.6vs20.6% P=0.72 OR1.067) and distortions(71.7%vs74.7% P=0.64 OR0.857). In addition, among 37 breast cancer patients who did not harbor the mammographic findings above (26 dense and 11 non dense breasts), the average mass length was significantly larger in dense (13.6mm) than non-dense breast (9.9mm) (P=0.018 used Welch's t test), respectively. Conclusion Results of our present study did demonstrate that detection of malignancy in those with mammographic dense breast is more difficult. Therefore, in those harboring dense breast in mammography, addition of other modalities such as US could improve the detection of breast carcinoma. Citation Format: Takigami N, Tamaki K, Kamada Y, Uehara K, Terukina S, Ishida T, Miyashita M, McNamara KM, Tamaki N, Sasano H. Comparison of mammography findings between dense and non dense breast in Japanese subjects: The potential limitation of routine mammography [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P5-01-03.