Background: For the evaluation of nonpalpable lesions of the breast, image-guided 14-gauge automated needle biopsy is increasingly replacing wire-localized excision. When ductal carcinoma-in-situ (DCIS) is diagnosed at core biopsy, invasive cancer is found in approximately 17% of excision specimens. These so-called DCIS underestimates pose a problem for patients and surgeons, because they generally cause extension of treatment. We evaluated DCIS underestimates in detail to assess reasons for missing the invasive component at core biopsy. This evaluation also included a histological comparison with true DCIS (DCIS at core biopsy and excision).
Methods: Between 1997 and 2000, DCIS was diagnosed at 14-gauge needle biopsy in 255 patients. In 41 cases (16%), invasive cancer was found at excision. We performed a thorough histopathological and radiological review of all these DCIS underestimates, including a histological comparison with core biopsy specimens of 32 true DCIS cases. We assessed the main reason for missing the invasive component at core biopsy.
Results: Causes for DCIS underestimates were categorized into "mainly radiological" (n = 20), "mainly histopathological" (n = 15), and "histological disagreements" (n = 6). High-grade DCIS and periductal inflammation in core biopsies made a DCIS underestimate 2.9 and 3.3 times more likely, respectively.
Conclusions: A variety of radiological and histopathological reasons contribute to the DCIS underestimate rate. Approximately half of these are potentially avoidable.