Abstract P5-02-04: Study on over-diagnosis of high-precision breast cancer screening ∼ Consideration from epidemiological point of view

Abstract

Abstract <Introduction> In breast cancer screening, it has been attempted to combine US with MMG. For relatively small breasts and dense breasts, there is the opinion that this combination is useful. On the other hand, the problem of over-diagnosis of breast cancer screening has been raised. We've been breast cancer screening with US/MMG combination method since 2005. The results were examined from the epidemiological point of view. <Subjects and Methods > Breast cancer discovery rate through US/MMG screening at our facility from 2005 to 2014 was considered. The medical examination was performed on 35,353 women. Kagawa Prefecture, in which our facility is located has had 100 percent breast cancer registration for more than 10 years. We have compared the breast cancer registration of 2013 with our examination results. <Results> Asymptomatic breast cancer detection rate in our breast cancer screening was 0.6%. ４６% of the detected cancer was DCIS. Low-grade DCIS (Van Nuys 1 and 2) accounted for three-quarters of DCIS. In invasive carcinoma, 10 mm or less of luminal A type was 17%, other luminal types 19%, non-luminal types 5% and unclassified 6%. If our facility's highly precise breast cancer medical examination were performed throughout Kagawa Prefecture, DCIS would be found in 860 cases, 10 mm or less of luminal A type found in 276, other luminal type found in 320 and non-luminal type found in 70 cases per year.Compared to the Kagawa Prefecture breast cancer registered in 2013, DCIS was 6.6 times larger than the registered data, 10 mm or less of luminal A 2.9 times larger, other luminal types 1.1 times larger, and non-luminal types 1.2 times larger. The differences between the registered data and our findings for DCIS and 10mm or less of luminal A type are remarkable. <Conclusion> With the US/MMG combination method, the detection rate of DCIS and 10 mm or less of luminal A type have been excessive. Many type of DCIS and tiny luminal A type must exist latently. When performing a high-precision breast cancer screening, it is necessary to note such over-diagnosis. Furthermore, it is also necessary to re-examine the pathology diagnostic criteria of DCIS. Citation Format: Takebe K, Arai T. Study on over-diagnosis of high-precision breast cancer screening ∼ Consideration from epidemiological point of view [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P5-02-04.