Purpose: Sentinel lymph node (SLN) biopsy has become a new standard procedure in the treatment of patients with early breast cancer. Furthermore, many institutions have begun offering the sentinel lymph node biopsy without simultaneous axillary dissection as a possible standard procedure when the SLN was free from tumors. For appropriate intraoperative decision making on the presence of cancer cells in axillary lymph nodes, a fast and accurate method to assess the SLN is required. The authors performed a prospective investigation of the relative merits of rapid cytokeratin immunohistochemical (IHC) staining of the SLN removed during the operations of breast cancer patients.
Methods: Between December 2002 and August 2003, 38 patients with T1and T2 breast cancer were enrolled after undergoing successful sentinel lymph node biopsy. A total of 60 sentinel lymph nodes (mean number, 1.58) were biopsied and first examined by hematoxylin-eosin (H&E) staining. All the tumor free sentinel lymph nodes by H&E stained section were immunostained for cytokeratin using a rapid immunohistochemical assay (Cytokeratin (PAN), 1：50,Newcastle, UK) during the operation. Finally, the sentinel lymph nodes were submitted for paraffin embedding and serial section after surgery. Both H&E stained and cytokeratin immunostained sections were also performed.
Results: This technique has a turnaround time of less than 20 minutes during the operation. Rapid IHC staining revealed 4 positive sentinel lymph nodes that were negative for metastasis by H&E staining. Among these false negative 4 cases, two cases had problems with the frozen section of H&E staining and the other 2 cases had problems due to micrometastasis. This study showed a sensitivity of 88.89%, a specificity of 100%, an accuracy of 98.33%, and a negative predictive value of 98.08%. The false-negative case (1 of 52), which was negative on H&E staining and rapid IHC staining during the operation, was disclosed as positive only after a serial permanent section examination with IHC stain.
Conclusion: The introperative examination of sentinel lymph nodes is a highly accurate and effective way of predicting the axillary lymph node status of patients with breast cancers. This may be a promising technique in deciding whether to spare axillary lymph node dissection for the patient in the operating room. (Journal of Korean Breast Cancer Society 2004;7:154-160)
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