Comparability of Different Pathologic Protocols in Sentinel Lymph Node Evaluation: An Analysis of Two Step-Sectioning Methods for the Same Patients with Breast Cancer (Report‪)‬

Sentinel lymph nodes (SLNs) are recognized as the first lymph nodes to receive lymphatic drainage from a primary tumor before spreading to other lymph nodes. The SLN dissection is widely performed for patients with a range of cancers, especially those with breast cancer. The status of SLNs accurately reflects the presence or absence of metastases in the axillary lymph nodes and can also help in determining the tumor stage and appropriate surgical strategies for further axillary lymph node dissection. (1) Because of its very high negative predictive value regarding the status of the remaining axillary lymph nodes, a negative SLN dissection can spare patients with breast cancer who have lymphedema pain, numbness, and restricted shoulder motion from undergoing complete axillary lymph node dissection. (2) Although SLN evaluation has been accepted as a standard surgical procedure in early breast cancer, there still is no consensus on the pathologic protocol that should be used on an SLN specimen. (3) A recent survey of the histopathologic protocols used in Europe for the examination of SLNs of patients with breast cancer showed that 123 different histologic protocols exist across 240 laboratories. (4) The existing pathologic procedures for SLNs range from simple approaches to more extensive examinations of step or multilevel sections with or without cytokeratin immunostaining and/or sophisticated molecular techniques. (5) The more thorough that pathologists are with SLN evaluations, the greater the number of metastatic foci detected. An examination of a limited number of pathologic sections may result in an underestimation of the metastatic potential of breast carcinoma. (6) The step- or multilevel-sectioning method is currently the agreed-upon "standard" for the pathologic examination of SLNs. (7-8) However, at present, no widely accepted pathologic protocol for SLN evaluation is considered the "standard." Previous studies in the literature have suggested that it may be more efficient to obtain fewer sections at larger intervals than to obtain many sections at small intervals for each slide, as a greater volume of SLN can be examined by the former than the latter method. (9) Relatively few studies have compared the different step-sectioning methods in separate groups of patients. (7,10) This study aims to statistically compare the yields of 2 different step-sectioning methods. For each patient with breast cancer, a 20-[micro]m section, representative of a smaller interval, and a 150-[micro]m section, representative of a larger interval, were examined.