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 carcinoma in situ (DCIS). Between October 2002 and January 2006, 47 patients with DCIS underwent wide excision after radio-guided lesion localisation; 44 of them (93.6%) had simultaneous SLN mapping. SLNs were analysed by 250 micron step-sectioning by H&E and immunohistochemical evaluation. The histological investigation verified pure breast DCIS in 36 cases (76.6%), DCIS with microinvasion in 7 cases (14.9%) and lobular in situ breast cancer in 4 cases (8.5%). SLNs were identified in 40 cases (91%) and removed in 39 cases: an average of 1.5 SLNs per patient. In 4 patients (9%) SLN biopsy was unsuccessful because of the lack of migration of radiocolloid substance. In these cases, axillary sampling was performed. In 1 case (2.3%), only a parasternal SLN was detected; this was not removed. Histological analysis of SLNs and axillary lymph nodes with haematoxylin and eosin or cytokeratin immunohistochemistry did not prove metastases. On the basis of international data and our present results, routine SLN biopsy is not 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.