Stereotactic breast biopsy: Comparison of histologic underestimation rates with 11-and 9-gauge vacuum-assisted breast biopsy

OBJECTIVE. The purpose of this study was to compare histologic underestimations at stereotactic 11- and 9-gauge vacuum-assisted breast biopsy. MATERIALS AND METHODS. The reports of 1,223 consecutive stereotactic vacuum-assisted breast biopsies were retrospectively reviewed. An 11- gauge device was used to perform 828 and a 9-gauge device to perform 395 biopsies. The pathologic results were reviewed for all cases. Biopsy results of atypical ductal hyperplasia and ductal carcinoma in situ were compared with the pathologic results after surgical excision. Underestimation was defined as the need to upgrade atypical ductal hyperplasia to ductal carcinoma in situ or invasive carcinoma at surgery and to upgrade ductal carcinoma in situ to invasive carcinoma. Statistical significance was determined with the chi-square test and 95% CI. RESULTS. In the 11- gauge group, 12 ( 26%) of 46 cases of atypical ductal hyperplasia were upgraded to ductal carcinoma in situ and one ( 2%) of the cases to invasive carcinoma. In the 9-gauge group, six ( 22%) of 27 cases of atypical ductal hyperplasia were upgraded to ductal carcinoma in situ and two (7%) of the cases to invasive carcinoma. In the 11- gauge group, 35 (28.7%) of 122 cases of ductal carcinoma in situ were upgraded to invasive carcinoma. In the 9-gauge group, 10 (23%) of 44 cases of ductal carcinoma in situ were upgraded to invasive carcinoma. CONCLUSION. There was no statistically significant difference between 11- gauge biopsy and 9-gauge biopsy in underestimation of atypical ductal hyperplasia and ductal carcinoma in situ.