The impact of sentinel lymph node biopsy in patients with a core biopsy diagnosis of ductal carcinoma in situ

When ductal carcinoma in situ (DCIS) is found on core biopsy, histological underestimation can occur due to sampling error. When an invasive cancer is subsequently found, another operation is required for nodal staging. Sentinel lymph node biopsy (SLNB) enables nodal staging at the same operation. We examine the value of SLNB in patients with a preoperative diagnosis of DCIS focusing on the need for reoperation. Patients with a preoperative core biopsy of DCIS underwent SLNB at the time of definitive surgery. The results of SLNB in relation to histological upstaging were analyzed. One hundred and seven patients with a core biopsy diagnosis of DCIS underwent simultaneous SLNB at the time of definitive surgery. SLNB was successful in 103 patients (96.3%) and 12 (11.7%) had SLN metastases. Thirty-two patients (29.9%) had histological upstaging and SLN was positive in nine (28.1%). Seventy-five patients had "pure DCIS" but three (4%) had SLN metastases. The presence of a palpable mass and radiological mass lesion were associated with histological upstaging. If SLNB were not performed, 32 patients (29.9%) with upstaging would require another surgery to stage the axilla. In the present series, 84% of these patients had appropriate axillary staging without the need for a second operation. Underestimation of invasive disease was frequent on core biopsy. Performing SLNB during definitive surgery allowed correct nodal staging in a single operation. SLN metastasis was rare in patients with "pure DCIS" on final pathology. However, additional systemic treatment may be indicated for patients with SLN micrometastases.