How is sentinel lymph node (SLN) biopsy performed in the surgical treatment of breast cancer?

Updated: Feb 13, 2019
  • Author: Mary Jo Wright, MD; Chief Editor: James Neal Long, MD, FACS  more...
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The best results with SLN biopsy are achieved with the combination of careful intraoperative digital examination and lymphatic mapping. [19] The latter technique involves injecting radioisotope (technetium-99m sulfur colloid) alone or radioisotope plus a patent blue dye (Lymphazurin or methylene blue) into the tissues of the breast.

Several techniques of injection are available, including subareolar, peritumoral, intradermal, or intraparenchymal. The technique of injection may not be as important as the skill and experience of the surgeon with the chosen technique and with SLN identification in general. With SLN dissection, typically 1-3 lymph nodes are removed and tested for nodal metastasis with hematoxylin and eosin (H&E) stain and immunohistochemistry (IHC) with an anticytokeratin cocktail.

SLNs may be checked intraoperatively by imprint touch preparation, frozen section, or real-time polymerase chain reaction (RT-PCR). Intraoperative evaluation allows for immediate axillary lymph node dissection if an SLN is unequivocally positive for nodal metastasis. The American Society of Clinical Oncology (ASCO) guideline recommendations for SLN biopsy in early stage breast cancer include axillary lymph node dissection after detection of a positive SLN. [20] However, isolated tumor cells detected by specialized techniques such as IHC and RT-PCR remain of uncertain significance.

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