Role of primary tumor characteristics in predicting positive sentinel lymph nodes in patients with ductal carcinoma in situ or microinvasive breast cancer.

BACKGROUND: We determined the incidence of positive sentinel lymph nodes (SLNs) in patients with ductal carcinoma in situ (DCIS) or microinvasive breast cancer (MIC) and the predictive factors of SLN metastasis in these patients.
METHODS: Of 4,503 patients who underwent SLN dissection between March 1994 and March 2006 at our institution, we identified those with a preoperative diagnosis or final diagnosis of DCIS or MIC. Clinicopathologic factors were examined by logistic regression analysis.
RESULTS: Of the 624 patients with a preoperative diagnosis of DCIS or MIC, 40 had positive SLNs (6.4%). Of the 475 patients with a final diagnosis of DCIS or MIC, 9 had positive SLNs (1.9%). Clinical DCIS size >5 cm was the only independent predictor of positive SLN for patients with a preoperative diagnosis and patients with a final diagnosis of DCIS or MIC. Core biopsy as the method of preoperative diagnosis and DCIS size >5 cm were independent predictors for a final diagnosis of invasive carcinoma in the 149 patients who had a preoperative diagnosis of DCIS or MIC.
CONCLUSIONS: SLN dissection for patients with a diagnosis of DCIS should be limited to patients who are planned for mastectomy or who have DCIS size >5 cm. Patients who have a core-needle biopsy diagnosis of DCIS have a higher risk of invasive breast cancer on final pathologic assessment of the primary tumor. This information can be used in preoperative counseling of patients with DCIS regarding the timing of SLN biopsy.