Serial sectioning of sentinel nodes in patients with breast cancer: A pilot study

Background: Recent reports indicate that the sentinel node, defined as the first regional lymph node to receive lymphatic fluid from the breast, accurately represents the metastatic status of the primary breast cancer. However, routine single section examination of the regional nodes, including the sentinel node, underestimates the true incidence of metastases. The goal of this study is to determine whether multiple sectioning of sentinel nodes will detect occult metastases in operable breast cancer. Methods: Nineteen patients with invasive breast cancers were injected with technetium-99m sulfur colloid solution around the tumor or at the biopsy site before lumpectomy and axillary lymph node dissection (ALND) or mastectomy. The labeled sentinel lymph nodes (SLND) were bivalved, and a central section was taken for hematoxylin and eosin (H & E) examination. The sentinel nodes of 13 patients, which were reported to be negative for metastases, were serially sectioned at 0.5-mm intervals and stained with H & E and a cytokeratin stain, CAM 5.2. Results: In the 13 node-negative patients, occult metastases were found in the sentinel nodes of 3 patients (23%). Two were seen on H & E and one by cytokeratin stain. The mean numbers of SLND and ALND in this series were 2.6 and 12.5, respectively, and the average number of sections for the two groups was 14 and 1, respectively. Conclusion: Multiple sectioning of the sentinel node or nodes detects occult metastases and changes the staging of breast cancer.