Background: Sentinel lymph node biopsy (SLNB) is a widely accepted alternative to axillary lymph node dissection in invasive breast cancer. Its role in ductal carcinoma-in-situ (DCIS) is unclear. The purpose of this study was to determine factors associated with the subsequent diagnosis of invasive disease and to determine the role of SLNB when performing a mastectomy for DCIS.
Methods: A retrospective study was conducted of all mastectomies performed on patients with a preoperative diagnosis of DCIS between 2000 and 2005 at a single tertiary-care institution.
Results: Ninety mastectomies for DCIS were included, 54 (60%) of which were performed with concurrent SLNB. Of 44 patients diagnosed preoperatively with DCIS by core biopsy only, 34 patients (63%) had a concurrent SLNB, while 10 patients (28%) were treated with mastectomy alone (P < .01). Overall, 30 patients (33%) had invasive disease, 22 of whom received concurrent SLNB. Seven SLNB patients (13%) had positive SLNs. On univariate analysis, multifocality (P = .03), multicentricity (P = .01), comedonecrosis (P = .01), and diagnosis by core biopsy (P < .001) were associated with invasive disease on pathology. On multivariate analysis, comedonecrosis (P = .04) and diagnosis by core biopsy (P < .01) were independent predictors for invasion. There was no statistically significant predictor for sentinel lymph node metastasis.
Conclusions: Approximately one-third of patients with DCIS treated with mastectomy at our institution later had invasive disease, and factors associated with invasion have been identified. On the basis of our results, routine SLNB is recommended in this patient population.