Importance of sentinel lymph node biopsy in surgical therapy of in situ breast cancer.

The aim of this retrospective study was to determine the rate of sentinel lymph node (SLN) positivity in patients with a final diagnosis of ductal in situ cancer (DCIS) of the breast. Between October 2002 and January 2007, 57 patients with DCIS underwent wide excision after radio-guided lesion localization; 53 of them (53/57, 93%) had participated in simultaneous SLN mapping. SLNs were analysed by 250-micron step-sectioning with haematoxylin and eosin staining and immunohistochemical evaluation. The histologic investigation verified pure breast DCIS in 44 cases (44/57, 77.2%), DCIS with microinvasion in eight cases (8/57, 14%) and lobular in situ breast cancer in five cases (5/57, 8.8%). SLNs were identified in 49 cases (49/53, 92.5%) and removed in 48 cases (48/53, 90.6%), i.e. an average of 1.6 SLNs per patient. In four patients (4/53, 7.6%), the SLN biopsy was unsuccessful because of the failure of the radiocolloid substance to migrate. In these cases, axillary sampling was performed. In one case (1/53, 1.9%), only a parasternal SLN was detected; this was not removed. Histologic analysis of the SLNs and the axillary lymph nodes with haematoxylin and eosin or cytokeratin immunohistochemistry did not prove the presence of metastases. The international data and our present results suggest that routine SLN biopsy is not to be recommended in pure DCIS cases. If the final histology verifies an invasive or microinvasive tumour, or if mastectomy is to be performed, SLN mapping is suggested.