Lymphatic Mapping and the Significance of Sentinel Node Biopsy

ii Faculty The objective of this course is to teach the indications, techniques, and theoretical concepts of lymphatic mapping and sentinel node biopsy for breast cancer and melanoma. After participating in this course, surgeons should be able to begin to perform and evaluate lymphatic mapping and sentinel node biopsy with blue dye, radio-isotope, or a combination of both. The histopathologic methodology of sentinel node evaluation will be discussed. The techniques of lymphoscintigraphy for successful identification of lymph nodes will be described, and the clinical significance of micrometastases and ongoing clinical trials will be discussed. In keeping with the practice of publishing scientific material, the authors are responsible for the accuracy and completeness of the references and bibliographies published in this syllabus. Objective Understand the concept, purpose, and potential of in-traoperative lymphatic mapping to identify the senti-nel lymph node on the lymphatic drainage path from solid tumors. At the completion of the course, the surgeon should be able to communicate the following: 1. The definition of a sentinel node 2. Mapping agents used to identify the sentinel node 3. Controversies of probe-directed intraoperative mapping 4. The degree of training and experience required to undertake sentinel lymphadenectomy without subsequent complete lymphadenectomy 5. Multidisciplinary components of lymphatic mapping 6. The current status of sentinel lymphadenectomy for various solid tumors Outline I. The sentinel node concept and development of the sentinel node technique The concept of the sentinel node is predicated on the fact that the efferent lymphatic channel draining a primary tumor will lead directly to the first— " sentinel " —lymph node in the regional lymphatic basin. This lymphatic channel can carry malignant cells from a primary tumor to the sentinel node. The tumor cells can then lodge in the subcapsular sinus of the lymph node and proliferate into a nodal metastasis. Thus, the sentinel node is the lymph node most likely to harbor metastatic disease if a regional nodal metastasis is present. A. Feline model B. Early clinical studies using blue dye II. Introduction of probe-directed mapping The success of lymphatic mapping depends on identifying the first lymph node draining the primary tumor. However, when mapping is performed with a radiocolloidal agent, the number of hot lymph nodes will vary with the agent and with the interval between its injection and the surgical procedure. As the radiolabeled colloid flows along the lymphatic chain, the sentinel should be the first draining node …