Sentinel node biopsy in ductal carcinoma in situ patients

Background: Sentinel lymph node (SLN) mapping is an effective and accurate method of evaluating the regional lymph nodes in breast cancer patients. Th e SLN is the first node that receives lymphatic drainage from the primary t umor. Patients with micrometastatic disease, previously undetected by routi ne hematoxylin and eosin (H&E) stains, are now being detected with the new technology of SLN biopsy, followed by a more detailed examination of the SL N that includes serial sectioning and cytokeratin immunohistochemical (CK I HC) staining of the nodes, Methods: At Moffitt Cancer Center, 87 patients with newly diagnosed pure du ctal carcinoma in situ (DCIS) lesions were evaluated by using CK IHC staini ng of the SLN. Patients with any focus of microinvasive disease, detected o n diagnostic breast biopsy by routine H&E, were excluded from this study. D CIS patients, with biopsy-proven in situ tumor by routine H&E stains, under went intraoperative lymphatic mapping, using a combination of vital blue dy e and technetium-labeled sulfur colloid. The excised SLNs were examined gro ssly, by imprint cytology, by standard H&E histology, and by IHC stains for CK, All SLNs that had only CK-positive cells were subsequently confirmed m alignant by a more detailed histological examination of the nodes. Results: CK IHC staining was performed on 177 SLNs in 87 DCIS breast cancer patients. Five of the 87 DCIS patients (6%) had positive SLNs. Three of th ese patients were only CK positive and two were both H&E and CK positive. T herefore, routine H&E staining missed microinvasive disease in three of fiv e DCIS patients with positive SLNs. In addition, DCIS patients with occult micrometastatic disease to the SLN underwent a complete axillary lymph node dissection, and the SLNs were the only nodes found to have metastatic dise ase. Of interest, four of the five node positive patients had comedo carcin oma associated with the DCIS lesion, and one patient had a large 9.5-cm low grade cribriform and micropapillary type of DCIS. Conclusions: This study confirms that lymphatic mapping in breast cancer pa tients with DCIS lesions is a technically feasible and a highly accurate me thod of staging patients with undetected micrometastatic disease to the reg ional lymphatic basin. This procedure can be performed with minimal morbidi ty, because only one or two SLNs, which are at highest risk for containing metastatic disease, are removed. This allows the pathologist to examine the one or two lymph nodes with greater detail by using serial sectioning and CK IHC staining of the SLNs. Because most patients with DCIS lesions detect ed by routine H&E stains do nor have regional lymph node metastases, these patients can safely avoid the complications associated with a complete axil lary lymph node dissection and systemic chemotherapy. However, DCIS patient s with occult micrometastases of the regional lymphatic basin can be staged with higher accuracy and treated in a more selective fashion.