Role of sentinel lymph node biopsy (SLNB) and preoperative MRI in the management of patients with pure high-grade ductal carcinoma in situ (DCIS).

Abstract

87 Background: The overall incidence of SLN metastases in pure DCIS is < 1% and the results of SLNB do not usually impact treatment or survival but adds significant surgical morbidity. In addition, there is no evidence regarding the role of preoperative MRI in the management of DCIS. The purpose of our study was to identify the efficacy of SLNB and the benefit of preoperative MRI in high-grade DCIS. Methods: We performed retrospective review of 364 patients with DCIS, identified through our cancer registry database, that were seen from 2003 to 2012 at our institution. Of these, 62 patients were diagnosed with high-grade DCIS (Grade 3 or 2 with comedonecrosis) by core needle biopsy, and underwent SLNB. The remaining 302 patients had either low-grade DCIS or did not have a SLNB. Results: Median age was 56 years (range 33-80). Sixty two patients had high-grade DCIS on definitive excision and 2/62 patients were noted to have small invasive focus of disease. 15/62 (24.19%) patients underwent mastectomy and 47/62(78.1%) underwent lumpectomy. No patient had a positive SLN (0/62). 15/62 (24.2%) patients had breast MRI preoperatively and among them, in 5 (33.3%) patients, MRI findings changed the surgical decision to mastectomy. Among these 5 mastectomy patients, four of them (80%) had pathologically confirmed findings consistent with preoperative MRI suspicions. In lumpectomy patients, close margin of less than 1mm was seen in 4/9 (44.4%) patients with staging MRI and in 24/38 (63.15%) patients without MRI (p = 0.45. Fisher’s exact test). However the positive margin leading to re-excision was seen in 2/9 (22.2%) patients who underwent lumpectomy with staging MRI, and 9/38 (23.6%) patients who underwent lumpectomy without staging MRI. Conclusions: In our study, no patient with high grade DCIS had a positive sentinel node suggesting that routine sentinel node biopsy is not necessary in DCIS patients. The use of MRI changed the surgical planning in 33.3% of patients, but did not improve the surgeon's ability to achieve clear margins.