Predictors of invasive breast cancer in patients with an initial diagnosis of ductal carcinoma in situ: a guide to selective use of sentinel lymph node biopsy in management of ductal carcinoma in situ.

Background: The role of sentinel lymph node biopsy (SLNB) in patients with an initial diagnosis of ductal carcinoma in situ (DCIS) has not been well defined. The purpose of our study was to determine when the risk of finding invasive disease on final pathology in patients with an initial diagnosis of DCIS was sufficiently high to justify use of SLNB.
Study Design: The records of 398 consecutive patients from our prospective database with an initial diagnosis of DCIS, treated between July 1999 and December 2002, were analyzed. Associations between clinical and pathologic factors and patient selection for SLNB and outcomes were analyzed for significance using univariate and multivariate analyses.
Results: Of the 398 patients, 80 (20%) were found to have invasive disease on final pathology. Multivariate analysis revealed 4 independent predictors of invasive cancer on final pathology: 55 years of age or younger (odds ratio [OR], 2.19; p = 0.024), diagnosis by core-needle biopsy (OR, 3.76; p = 0.006), mammographic DCIS size of at least 4 cm (OR, 2.92; p = 0.001), and high-grade DCIS (OR, 3.06; p = 0.002). A total of 141 patients (35%) underwent SLNB as a component of their initial operation. Multivariate analysis revealed that the presence of comedonecrosis (OR, 2.69; p = 0.007) and larger mammographic DCIS size (OR, 1.18; p = 0.0002) were independent predictors of patients' undergoing SLNB. Of these 141 patients, 103 (73%) were diagnosed by core-needle biopsy, 42 (30%) had invasive disease on final pathology, and 14 (10%) had a positive sentinel lymph node: 12 (86%) by hematoxylin and eosin staining and 2 by immunohistochemistry. The only independent predictor of a positive SLN was the presence of a palpable tumor (OR, 4.28, p = 0.042). Of these 14 patients with a positive sentinel node, only 11 (79%) had invasive cancer on final pathology.
Conclusions: SLNB should not be performed routinely for all patients with an initial diagnosis of DCIS. Risks and benefits of SLNB should be discussed with patients who are younger, are diagnosed by core-needle biopsy, or have large or high-grade DCIS.