OBJECTIVETo evaluate the impact of lesion size on the detection rate of non-palpable breast malignant lesions and determine whether lesion size should prompt biopsy of non-palpable breast lesions.

METHODSThe study included 816 ultrasonographically detected non-palpable breast lesions. We divided the lesions into five groups based on their largest diameters: ≤0.5cm, 0.6-1.0cm, 1.1-1.5cm, 1.6-2.0 cm, and >2.0 cm. The detection rate of malignancies of different sizes were compared among these lesions, Breast Imaging Reporting and Data System (BI-RADS) category 2-3 lesions, and BI-RADS grades 4-5 lesions. The feasibility of using lesion size as biopsy indicator for BI-RADS category 2-3 non-palpable breast lesion was analyzed using ROC curve.

RESULTSOf these 816 lesions, 100 (12.3%) were found to be malignant lesions. The detection rate of malignancy significantly increased along with the increase of lesion size (P<0.05). When the BI-RADS category was not considered, the frequency of malignancy in the >2.0 cm group was significantly higher than in other groups (P<0.05) The frequencies of malignancy in the 0.6-1.0 cm group, 1.1-1.5 cm group, and 1.6-2.0 cm group were higher than that in ≤0.5 cm group, but the difference was not significant (P>0.05) For BI RADS category 4 and 5 lesions, the frequency of malignancy in >2.0 cm group was higher than in other groups, but significant difference was only seen between >2.0 cm group and ≤0.5 cm group (P<0.05).

CONCLUSIONSLesion size may influence the detection rate of malignancy of non palpable breast lesions, and can be used as biopsy indicator of non palpable breast lesions in BI-RADS 2,3 category When we use 1.25cm as threshold,the sensitivity and specificity may be satisfying.