Sentinel Lymph Node Biopsy
by Roel Tolentino, M.D.
This article starts below.
Lymph nodes play a key role in our body's immune system. They filter bacteria, toxins, as well as cancer cells.
The standard approach to determine whether breast cancer has spread to lymph nodes in the armpits is the surgical removal of the lymph nodes, which are then sent to the laboratory for biopsy. Today an alternative, less invasive method to determine breast cancer spread to the lymph nodes is increasingly being used: sentinel lymph node biopsy.
Less invasive alternative
Sentinel lymph node biopsy is a procedure that involves identifying and removing the first node (or nodes) to which the cancer cells spread after leaving the area of the primary tumor. The presence of cancer cells in this node alerts the doctor that the tumor has spread to the lymphatic system.
To identify the sentinel lymph nodes, the surgeon injects a radioactive tracer, a blue dye, or both, near the tumor. Combining the radioactive tracer and blue dye provides better results with a low false negative rate of five to ten percent. The surgeon uses a scanner (gamma probe) to find the sentinel lymph nodes containing the radioactive substance or looks for the lymph nodes stained with the dye. The surgeon then removes the sentinel nodes to check for the presence of cancer cells. If the removed sentinel node is cancer-free, additional lymph node surgery may be avoided.
Who should have this biopsy?
Sentinel lymph node biopsy may be done in patients with early stage breast cancer (T1 or T2, N0). The procedure may also be performed after neoadjuvant therapy, axillary radiotherapy, and prior axillary dissection for breast cancer.
The 2005 American Society for Clinical Oncology Guideline states that breast cancer patients with no palpable lymph nodes in the axilla whose breast tumor is five centimeters or smaller are appropriate candidates for lymph node mapping and sentinel node sampling.
Benefits of sentinel node biopsy
Sentinel lymph node biopsy offers several benefits, such as reduced complications, better quality of life, and better arm functioning compared to formal axillary lymph node dissection. It should be the treatment of choice for patients who have early-stage breast cancer with clinically-negative nodes.
Many surgeons have questioned the survival of patients who undergo sentinel node biopsy. However, a recent study revealed that the survival rate among node-negative breast cancer patients who had sentinel node biopsy did not differ significantly from that of node-negative breast cancer patients who underwent level I-II axillary lymph node dissection. Thus, it is recommended that sentinel node biopsy should replace axillary lymph node dissection as the primary tool for the axillary staging of breast cancer in selected node-negative patients.