Which sentinel nodes are removed during a sentinel lymph node biopsy using Technetium (Tc-99m)?

From the Guidelines

During a sentinel lymph node biopsy using technetium-99m, the surgeon removes the specific lymph nodes that first receive lymphatic drainage from the tumor site, typically 1-5 nodes, which are identified by injecting technetium-99m sulfur colloid near the tumor before surgery and detected using a handheld gamma probe during surgery. These sentinel nodes are the first lymph nodes encountered in the lymphatic drainage of the breast and are generally identified by lymphatic mapping using blue dye, radiolabeled colloid, or both 1. The radioactive tracer travels through the lymphatic channels to the first draining lymph nodes, which are then detected using a handheld gamma probe during surgery 1. The surgeon removes all lymph nodes that show significant radioactive uptake, typically defined as nodes with counts greater than 10% of the hottest node.

• The exact number of sentinel nodes removed varies depending on the individual patient's lymphatic drainage pattern.
• The use of lymphoscintigraphic imaging before surgery can help identify the location of the sentinel nodes and facilitate their detection during surgery 1.
• The removed sentinel nodes undergo thorough pathological examination to determine if cancer has spread beyond the primary site, which guides further treatment decisions.
• The targeted approach of sentinel lymph node biopsy allows for accurate staging while minimizing the morbidity associated with complete lymph node dissection 1.

From the Research

Sentinel Lymph Node Biopsy Using Technetium (Tc-99m)

• The sentinel lymph node (SLN) biopsy technique has been developed as a possible alternative to axillary lymph node dissection (ALND) for breast cancer patients 2.
• The SLN is defined as the first node in the regional lymphatic basin that receives drainage of the primary tumor 2.
• Technetium-99m (Tc-99m) is used as a radiopharmaceutical for lymphoscintigraphy to identify the SLN 3.
• Tc-99m-sulfur colloid (99mTc-SC), 99mTc antimony trisulfide colloid (99mTc-ATC), and 99mTc nanocolloidal albumin (99mTc-CA) are commonly used radiopharmaceuticals for SLN detection 3.
• Intradermal periareolar injection of Tc-99m can accurately identify the SLN in breast cancer patients 4.
• The use of small-sized Tc-99m-labeled tin colloids has been shown to provide higher detection and identification rates of SLNs compared to regular-sized colloids 5.

Removed Sentinel Nodes

• The SLN biopsy technique involves the removal of the first lymph node (or nodes) that receive drainage from the primary tumor 2, 3.
• The removed SLN is then evaluated for the presence of cancer cells to determine the need for further treatment 2, 4, 5.