To analyze the clinicopathological characteristics of patients with false negative breast cancer diagnosed by ultrasound examination, and explore measures to reduce the missed diagnosis rate of breast cancer.

According to the inclusion and exclusion criteria, the data of 68 cases of false-negative breast cancer diagnosed by ultrasound in the Tumor Hospital of Gansu Province from January 2011 to June 2016 were analyzed retrospectively. The relationship between clinicopathological factors (ultrasound blood flow type, Adler classification, etc) and BI-RADS ultrasound classification and the relationship between BI-RADS mammography classification and BI-RADS ultrasound classification were analyzed. The one-way ordered data and the two-way ordered rank data were analyzed by the Kruskal-wallis H test. The pairwise comparison between groups was performed by the Bonferroni-Dunn’s method.

The number of patients with BI-RADS category 1, 2 and 3 lesions was 2, 5 and 14; 0, 1 and 7; 1, 2 and 13; 4, 12 and 7 among the patients with peripheral, penetrating, internal and lacking blood flow types, respectively. The number of patients with BI-RADS category 1, 2 and 3 lesions was 2, 12 and 7; 3, 7 and 26; 2, 1 and 8 among the patients with Adler classification 0, 1, 2 lesions. There were significant differences in BI-RADS category of breast cancer missed by ultrasound among patients with different ultrasound blood flow types and different Adler classification (χ²=14.756, 6.829; P=0.002, 0.033). The patients with different BI-RADS mammography category showed significant difference in BI-RADS ultrasound category (χ²=9.574, P=0.023). After mammography, 17 patients were newly diagnosed with BI-RADS category 4 lesions and the cases of missed diagnosis declined by about 25%. The large majority of breast cancer missed by ultrasound was at early stage (Tis: 22 cases; T_1mic: 14; T_1c: 17; T₂: 6).

Early stage, small lesions, special pathological types and atypical blood flow features are main factors for misseddiagnosis of breast cancer by ultrasound. Additional mammography can improve the diagnostic accuracy of ultrasound to diagnose breast cancer, but it still has certain limitations.