Cytokeratin-positive cells in sentinel lymph nodes in breast cancer are not random events: experience in patients undergoing prophylactic mastectomy.

BACKGROUND: The incidence of immunohistochemistry (IHC)-detected epithelial cell displacement in sentinel lymph node (SLN) biopsy is unknown. In the current study, we address this question by examining the pattern of SLN involvement in patients undergoing prophylactic mastectomy (PM) at Memorial Sloan-Kettering Cancer Center (New York, NY). METHODS: Between January 1999 and January 2003, 5275 patients underwent SLN biopsy. Unilateral or bilateral PM with SLN biopsy was performed in 143 (2.7%) patients, representing 163 PM cases. RESULTS: Occult carcinoma was identified in 13 of 163 (8.0%) PM specimens. Two patients with occult invasive carcinoma had positive SLNs (hematoxylin and eosin). In the remaining 150 PM cases without occult carcinoma (130 patients), 89% underwent IHC analysis of the SLNs. Of these 130 patients, 43 (33%) had one or more prior biopsies in their "cancer-free" breast, a median of 43 days (range, 3-314 days) before PM. A total of 310 SLNs were examined by IHC (mean, 2.3 lymph nodes per PM case). Only 1 of 130 (0.8%) patients without occult carcinoma had an IHC-positive SLN. This patient had Stage IIIC carcinoma of the contralateral breast. IHC-positive SLNs were not identified in any of the 43 patients with a history of prior biopsy. Therefore, only 1 IHC-positive SLN was detected in 310 (0.3%) lymph nodes examined. CONCLUSIONS: IHC-positive cells in SLNs are rare in the absence of cancer and are not the result of previous breast instrumentation. Although the prognostic significance of IHC-positive cells remains controversial, the current study suggests that they are not random events.

Predictors for nonsentinel node involvement in breast cancer patients with micrometastases in the sentinel lymph node.

Sentinel lymph node (SLN) biopsy in breast cancer allows for a more thorough pathologic assessment with serial sectioning and cytokeratin staining. This has resulted in increased detection of micrometastatic disease (tumor size < 2 mm) in the SLN. Unfortunately, the value of completion axillary dissection after finding micrometastatic disease in the SLN remains poorly defined. Over a 2-year period, a prospective database of 305 patients who underwent SLN biopsy for breast cancer at Baylor University Medical Center was reviewed. Eighty-four (27.5%) of the patients had evidence of metastatic disease in the SLN. Twenty-four of the 41 patients identified as having micrometastatic disease in the SLN underwent completion axillary lymph node dissection. In these patients, all nonsentinel nodes were further studied by serial sectioning and immunohistochemistry. The median age of these 24 patients was 52 years (range, 34-83). Their primary tumor stages were T1a and T1b (n = 5), T1c (n = 15), and T2 (n = 4). A total of 328 nonsentinel lymph nodes were examined, including 225 from patients with infiltrating ductal carcinoma (n = 17) and 103 from patients with infiltrating lobular carcinoma (n = 7). In the patients with infiltrating ductal carcinoma, no additional nodal metastases were identified, while in those with infiltrating lobular carcinoma, additional nodal disease was found in 5 lymph nodes (2 of 12 patients, 17%). Primary tumor characteristics were not predictive of additional nodal disease. These data suggest that patients with micro-metastasis in the SLN from infiltrating lobular carcinoma have a significant risk of harboring additional nodal disease and should undergo completion axillary dissection. However, those with micrometastatic disease from infiltrating ductal carcinoma have a very low incidence of additional metastasis and may not need completion axillary dissection.