2005 Volume 32 Issue 2 Pages 219-224
We have analyzed the cases of breast cancer detected during the breast cancer screening by ultrasonography (US) and further discussed usefulness of US. The rate of the cases requiring detailed examination was 3.7% (374/9, 978 subjects), while the detection rate of cancer was 0.29% (29/9, 978 subjects) . The 29 cases with breast cancer were all detected by US with the largest diameter of mass being 0.4-3.0 cm (a mean value 1.32 cm) and 26 (90%) of them were early-stage breast cancer. Of the US detected breast cancer, 52% (15/29) were detectable by palpation and 55% (12/22) were positive for mammography (MMG) . The mean diameter of masses of palpable/nonpalpable cases was 1.61±0.68 cm/1.01±0.28 cm respectively, indicating the diameters were significantly smaller in the nonpalpable cases. At the same time, the mean diameter of the masses detectable/nondetectable by MMG was 1.63±0.74 cm/0.91±0.31 cm respectively, indicating the diameters of masses were significantly smaller in the cases nondetectable by MMG and thus US excelled in detecting small masses, compared with clinical examination or MMG. On the other hand, when looking into the relationship between diameter of mass and conservative surgery, the masses with rather smaller diameters were observed in those having undergone the mastectomy. Moreover, among five cases with positive histological lymph node metastasis, four cases were early-stage breast cancers with the diameters less than 1.5 cm. Also, of those four cases three were nondetectable by both clinical examination and MMG. Meanwhile, as regards three out of five cases with minute calcification detected by MMG, the punctate hyper echo was detected even with US though only rough images of masses were portrayed for the rest of the two. Thus calcification in the hypoechoic area (LEA) was recognizable even by US to some extent.
In this study US excels anothers in the detecting of small breast cancer (especially invasive carcinoma) . With all these in mind, we consider US should be more proactively used for breast cancer screening.
