Predictors of invasive disease in breast cancer when core biopsy demonstrates DCIS only.

BACKGROUND AND OBJECTIVES: Ductal carcinoma in-situ on core biopsy does not preclude invasive disease within the excision specimen, resulting in the need for further axillary surgery. We sought to identify predictors of invasion when DCIS is present on core biopsy.
METHODS: From a database of 895 breast cancer patients, patients with DCIS on core biopsy who had subsequent surgical excision were identified. Their excision pathology and preoperative mammography were correlated with risk of invasion.
RESULTS: Patients (93) with a preoperative diagnosis of DCIS on core biopsy were identified. On excision, 31 patients (33%) had invasive carcinoma and 13 patients (14%) had microinvasion. A preoperative finding of calcification only on mammogram was associated with DCIS on excision (P = 0.014), whereas the presence of other mammographic features increased the risk of invasion. Size > or =5 cm on excision pathology was associated with increased risk of invasion (P = 0.002). Forty-eight percent (n = 11/23) of those diagnosed by ultrasound-guided core biopsy had frank invasion on excision compared to 21% (n = 12/57) diagnosed by stereotactic techniques (P = 0.017).
CONCLUSION: Mammographic features and tumor size can help predict invasion in patients who have DCIS on core biopsy. Patients who have features other than calcification on mammography or have tumor size > or =5 cm should be considered for a sentinel node biopsy. Copyright 2006 Wiley-Liss, Inc.