Sentinel lymph node biopsy in breast cancer

OBJECTIVE To evaluate the accuracy of sentinel lymph node biopsy (SLNB) to predict the axillary lymph node status in breast cancer patients and its clinical significance. METHODS Seventy patients with clinical TNM status T(1 - 2)N(0)M(0) underwent sentinel lymph node biopsy using Tc-99m sulfur colloid radiotracer and gamma probe, which was followed by standard axillary dissection. SLNB was compared with standard axillary dissection for its ability to reflect the final pathological status of the axillary nodes. The SLNs that were tumor negative in conventional HE staining were further evaluated using immunohistochemical stains for CK8, CK19 and KP-1 antibodies. RESULTS The sentinel lymph node (SLN) was successfully identified in 67 (95.7%) out of 70 patients. The number of sentinel nodes harvested ranged from 1 to 5 (average 1.6). The nonsentinel nodes ranged from 5 to 20 (average 12.3). Of the 67 patients, 29 (43.3%) had histologically positive axillary lymph nodes. SLN was positive in 24 patients with metastasis (35.8%), and in 7 patients without metastasis (10.4%). In 5 patients, SLN was negative for tumor with positive nodes. The accuracy of sentinel lymph node biopsy to predict the axillary lymph node status was 92.5% and the false negative rate was 7.5%. For tumors with diameter less than or equal to 2 cm, the accuracy was 100%. 65 SLNs that were negative for HE stain were also non-reactive to immunostain for CK8 and CK19 antibody. CONCLUSIONS SLNB can accurately predict the axillary lymph node status in most of breast cancer patients. The accuracy is about 100% in patients with T(1) lesions. Immunohistochemical staining at the same level of HE stain can not increase the detection of lymph node micrometastasis.