Underestimation of invasive malignancy on conventional core biopsy of breast

Vacuum-assisted biopsy (VAB) has established itself as the more sensitive diagnostic tool in the preoperative assessment of non-palpable breast lesions. The aim of this poster is to establish the underestimation rate of invasive malignancy on stereotactic 14 g wide-bore needle (WBN) biopsy of impalpable breast lesions presenting as microcalcifications.

Between August 2004 and March 2009, 41 cases of ductal carcinoma in situ (DCIS) were retrospectively identified from the screen-detected cases of microcalcifications who underwent stereo-tactic WBN biopsy with a 14 g automated device. The histology from these cases was compared with the post-surgery histology.

Thirteen out of 41 (32%) cases of DCIS were found to have invasive disease following surgery. In 9 out of 13 (69%) cases, the cluster of microcalcifications was greater than 20 mm in size. Only 2 out of 41 patients had more than 7 cores obtained from the lesion.

Our study is in line with the evidence in published literature that conventional core biopsy underestimates invasive malignancy substantially more (15 to 36%) when compared to VAB, where the underestimation is 0 to 19%. It also reveals, as do other studies, that the greater the size of the cluster of calcification, the higher the rate of underestimation. It would be ideal to perform VAB to interrogate microcalcifications, but until it becomes widely available on the NHS, we should aim to obtain at least ten or more cores from the lesion whenever possible and sample a wider area for larger lesions in order to obtain a more representative specimen.