Which sentinel lymph nodes are removed during a sentinel lymph node (SLN) biopsy?

From the Guidelines

The surgeon removes the first lymph node or group of lymph nodes encountered in the lymphatic drainage of the breast, generally identified by lymphatic mapping, during a sentinel lymph node biopsy. These sentinel nodes are identified by injecting a radioactive tracer, blue dye, or both near the tumor site before surgery, as described in the guidelines by 1. The tracer or dye travels through the lymphatic channels to the first draining lymph nodes, highlighting them for the surgeon.

Key Points to Consider

• Typically, one to five sentinel nodes are removed, though the exact number varies depending on the individual's lymphatic drainage pattern and the type of cancer, with studies such as 1 showing that removing more than 2 sentinel nodes can improve detection rates and reduce false negative rates.
• The use of a dual tracer, which combines blue dye and a radioisotope, can also lower false negative rates, as reported in studies like 1.
• The sentinel nodes are considered representative of the entire regional lymph node basin; if cancer cells have spread through the lymphatic system, they will likely be found in these nodes first.

Clinical Implications

• This targeted approach allows surgeons to assess lymph node status while avoiding the more extensive removal of lymph nodes, reducing the risk of complications like lymphedema, as noted in 1.
• The removed sentinel nodes are then examined by a pathologist to determine if cancer cells are present, which helps guide further treatment decisions, with the goal of minimizing morbidity and mortality while maintaining quality of life.

Evidence-Based Recommendations

• The most recent and highest quality study, 1, supports the use of sentinel lymph node biopsy as a preferred method for assessing lymph node status in patients with breast cancer, particularly those who have undergone neoadjuvant chemotherapy.

From the Research

Sentinel Lymph Nodes Removed During SLN Biopsy

The sentinel lymph nodes (SLNs) removed during a sentinel lymph node (SLN) biopsy are the first lymph nodes to which cancer cells are likely to spread from a primary tumor.

• The identification of these nodes is crucial for accurate lymph node staging and minimal morbidity 2.
• In melanoma and breast cancer, preoperative lymphoscintigraphy (LS) using peritumoral injections of tracer or injection adjacent to an excision biopsy site with dynamic imaging is used to visualize the lymphatic collectors and identify the SLNs 2.
• The SLNs are then removed and examined for cancer cells, allowing for highly accurate lymph node staging with minimal morbidity 2.

Techniques for Identifying SLNs

Different techniques are used to identify the SLNs, including:

• Lymphoscintigraphy, which is an essential part of radioguided sentinel lymph node biopsy 3.
• The use of fluorophores that are fluorescent under near-infrared light, injected during surgery, which is evolving as the preferred technique for patients with visceral tumors 2.
• The combination of radioguidance and vital blue dye technique, which has a high success rate in localizing the SLN in breast cancer surgery 3.

SLN Biopsy in Different Cancers

SLN biopsy is used in various types of cancer, including:

• Breast cancer, where it is a standard procedure to replace axillary lymph node dissection (ALND) in patients undergoing neo-adjuvant chemotherapy 4.
• Melanoma, where it has become a key component in the management of patients 5.
• Lung cancer, where the role of SLN biopsy is still being discussed and researched 5.