Identification and evaluation of axillary sentinel lymph nodes in patientswith breast carcinoma treated with neoadjuvant chemotherapy

Sentinel lymph node (SLN) biopsy has been shown to predict axillary metasta ses accurately in early stage breast cancer. Some patients with locally adv anced breast cancer receive preoperative (neoadjuvant) chemotherapy, which may alter lymphatic drainage and lymph node structure. In this study, we ex amined the feasibility and accuracy of SLN mapping in these patients and wh ether serial sectioning and keratin immunohistochemical (IHC) staining woul d improve the identification of metastases in lymph nodes with chemotherapy -induced changes. Thirty-eight patients with stage II or III breast cancer treated with neoadjuvant chemotherapy were included. In all patients, SLN b iopsy was attempted, and immediately afterward, axillary lymph node dissect ion was performed. If the result of the SLN biopsy was negative on initial hematoxylin and eosin-stained sections, all axillary nodes were examined wi th three additional hematoxylin and eosin sections and one keratin IHC stai n. SLNs were identified in 31 (82%) of 38 patients. The SLN accurately pred icted axillary status in 28 (90%) of 31 patients (three false negatives). O n examination of the original hematoxylin and eosin-stained sections, 20 pa tients were found to have tumor-free SLNs. With the additional sections, 4 (20%) of these 20 patients were found to have occult lymph node metastases. These metastatic foci were seen on the hematoxylin and eosin staining and keratin IHC staining. Our findings indicate that lymph node mapping in pati ents with breast cancer treated with neoadjuvant chemotherapy can identify the SLN, and SLN biopsy in this group accurately predicts axillary nodal st atus in most patients. Furthermore, serial sectioning and IHC staining aid in the identification of occult micrometastases in lymph nodes with chemoth erapy-induced changes.