Predictors of invasion in patients with core-needle biopsy-diagnosed ductal carcinoma in situ and recommendations for a selective approach to sentinel lymph node biopsy in ductal carcinoma in situ

BACKGROUND. Among patients with core-needle biopsy (CNB)-diagnosed ductal carcinoma in situ (DCIS), the guidelines for the selection of patients to undergo sentinel lymph node (SLN) biopsy are not well defined, and many patients with no invasion undergo an unnecessary SLN biopsy. The objective of this study was to identify the predictors of invasion in patients with CNB-diagnosed DCIS and, thus, to help determine the most appropriate candidates for SLN biopsy. METHODS. The authors retrospectively evaluated 200 consecutive patients with CNB-diagnosed DCIS who underwent final excision at their institution between May 1, 2002 and June 30, 2005. Demographic data, the size and type of lesion on imaging studies, histologic features of DCIS on CNB, the number of cores taken, and the number of cores involved by DCIS were correlated with invasion on excision and SLN biopsy outcome. RESULTS. Forty-one of 200 patients (21%) had invasive carcinoma diagnosed on final excision. Parameters that correlated with invasion were a mass lesion, lesion size >1.5 cm, high nuclear grade, and the presence of lobular cancerization on CNB. A multivariate logistic regression model was developed to predict invasion. At the time of breast surgery, 103 of 200 patients (52%) underwent SLN biopsy, and 34 had invasion diagnosed on final excision. Three patients had 1 positive SLN each. CONCLUSIONS. A mass lesion, lesion size >1.5 cm, and the presence of lobular cancerization on CNB were significant, independent predictors of invasion in patients with DCIS. The authors recommended the inclusion of these predictors in the guidelines for selecting patients for SLN biopsy to reduce the number of unnecessary procedures.