Indications for sentinel lymph node biopsy in patients with core- needle biopsy (CNB)-diagnosed ductal carcinoma in situ (DCIS)

Abstract

There is no indication for lymph node staging in patients with DCIS. However a significant number of core-needle biopsy (CNB)- diagnosed ductal carcinoma in situ (DCIS) operative specimens have invasive carcinoma, demanding further surgery for lymph node staging. The objectives of our study are to find predictive factors of invasive carcinoma and lymph node metastases in patients with pre-operative diagnosis of DCIS, and to establish criteria for lymph node staging with sentinel lymph node (SLN) biopsy. The authors retrospectively evaluated 140 consecutive patients with CNB/Vacuum assisted-diagnosed DCIS who were submitted to excision at our institution between August, 2000 and September 2007. Hi-grade DCIS was found in 41.4% of patients and 60% had necrosis. 120 patients had conservative breast cancer surgery. Lymph node staging was done simultaneously in 25 patients (5 with SLN biopsy) and in 35 patients after diagnosis of invasive carcinoma in the operative specimens. We found invasive carcinoma in 37.1% of patients and lymph node metastases in 5.7%. Median tumour size was 25,8 mm in patients with invasive carcinoma and 16,0 mm with pure DCIS (P=0.001). Necrosis and tumour grade on CNB were not predictive of invasive carcinoma on the operative specimens. Size was the predictive factor of invasive carcinoma and lymph node metastases. Only tumours≤10 mm had no lymph node metastases. Tumours greater than 40 mm had 37% lymph node metastases. In conclusion there is no indication for SLN biopsy in patients with tumours smaller than 10 mm but this procedure should be performed in tumours greater than 40 mm. Patients with tumours greater than 10 mm and smaller than 40 mm, who wish to avoid a second surgery for lymph node staging should also be offered SLN biopsy.