Sentinel lymph node biopsy is not warranted following a core needle biopsy diagnosis of ductal carcinoma in situ (DCIS) of the breast

INTRODUCTION: The role of sentinel lymph node biopsy (SLNB) in ductal carcinoma in situ (DCIS) is controversial. This study evaluates the risk of clinically relevant SLN metastasis following a core needle biopsy (CNB) diagnosis of pure DCIS. MATERIALS AND METHODS: Cases that underwent SLNB following a CNB diagnosis of pure DCIS at our institution over a 4.5 year period were evaluated. Parameters including the DCIS characteristics on CNB, the rate of upstaging to invasive carcinoma at excision and the SLNB result were recorded. RESULTS: Of 296 patients with a CNB diagnosis DCIS, 181 had SLNB (62%). The rate of invasion at excision in those undergoing SLNB was 30% (54/181). SLN metastasis was detected in 7/181 cases (4%), including 6 cases with isolated tumour cells only (3.5%) and only 1 case with a macro-metastatic deposit (0.5%). CONCLUSION: The risk of clinically significant SLN metastasis following a CNB diagnosis of DCIS is extremely low, despite a relatively high rate of upstaging to invasive carcinoma at excision. Our findings support the opinion that SLNB is not warranted following a CNB diagnosis of DCIS, particularly for those patients undergoing breast conservation surgery.