Accuracy and upgrade rates of stereotactic vacuum-assisted breast biopsy: Impact of number of core samples taken on malignancy underestimation rates.

Abstract

20 Background: There are multiple options for the diagnostic evaluation of mammographic suspicious breast abnormalities. The therapeutic strategy is often based on lesion histopathological information obtained from stereotactic vacuum-assisted biopsy (VAB). Therefore, accurate information obtained by VAB is very important. This study was performed to evaluate the impact of the number of core samples obtain during VAB on malignancy underestimation rates for mammographically detected breast lesions. Methods: The pathologic results of 128 consecutive stereotactic biopsies (January 2010-December 2010) were retrospectively reviewed. All biopsies were performed using a 9-gauge needle. Pathologic results of core biopsies and surgical excision were compared. Underestimation rates of malignancy were calculated and correlation was made with the number of core samples obtained. Results: Surgical excision was performed on 41% (52/128) lesions; 4 benign, 19 indeterminate and 29 malignant. Overall malignancy underestimation rate was 19%. There were 8 cases of ductal carcinoma in situ (DCIS) on core biopsy that were proven to be invasive ductal carcinoma (IDC) on surgical excision. There was one case of benign microcalcifications that was proven to be lobular neoplasia (LN). There was one case of an atypical papillary lesion that was proven to be DCIS. There was a significant difference (p=0.02) between the mean number of core samples taken in the underdiagnosed lesions (8, range 6-12) and the concordant lesions (10, range 6-20). Conclusions: In the case of stereotactic VAB diagnosis of breast lesions, the underestimation rate of malignancy is more likely with a lower number of core samples obtained.